Consumer Reports Article about Motor Oils...

[Wayne 962]

A recent discussion brought this up. Here's an electronic copy of that famous report that I cite in "101 Projects":

The Surprising Truth About Motor Oils
A Mobil commercial claims its oil "has been in more Indy 500 winners than any other oil." Quaker State shows an engine with a terminally corroded inside ---- what they imply could happen when you use another oil. Exxon's commercial for its Superflo oil urges motorists to "rely on the tiger."

Oil companies spend millions of advertising dollars each year to convince you that their oil can make your car's engine perform better and last longer. And purveyors of motor oil and engine "treatments" assert that their products offer engine protection that oil alone can't provide. In our most ambitious test project ever, we set out to discover whether such claims are fact or fancy.

One way to gauge the performance of motor oils is to test them on the road. We did just that, using a fleet of 75 New York City taxicabs. Indeed, the oil industry itself tests its oils in New York City taxis.

For 22 months, we tested the performance of 20 popular motor oils. Each of those oils met the industry's latest standards, as certified by a starburst symbol on the container. (See "It's not just oil," page 14.) We also tested Slick 50 Engine Treatment and STP Engine and Oil Treatments.

In addition to the taxicab tests, we had the oils' chemical and physical properties analyzed by an independent lab. We also surveyed our subscribers about their oil changing experiences and preferences, and we sent shoppers to quick lube centers across the country to assess the service (see page 17.) Finally, because changing the oil is just one part of car care, we've reviewed some other ways you can help keep your car running longer. That report begins on page 18.

Testing the oils
We put identical rebuilt engines with precisely measured parts into the cabs at the beginning of the test, and we changed their oil every 6000 miles. That's about twice as long as the automakers recommend for the severe service that taxicabs see, but we chose that interval to accelerate the test results and provide worst-case conditions. After 60,000 miles, we disassembled each engine and checked for wear and harmful deposits.

Our test conditions were grueling, to say the least. The typical Big Apple cab is driven day and night, in traffic that is legendary for its perversity, by cabbies who are just as legendary for their driving abandon.

When the cabs aren't on the go, they're typically standing at curbside with the engine idling ---- far tougher on motor oil than highway driving. What's more, the cabs accumulate lots of miles very quickly making them ideal for our purposes. Big-city cabs don't see many cold start-ups or long periods of highspeed driving in extreme heat. But our test results relate to the most common type of severe service ---- stop-and-go city driving.

Each of the 20 oils we studied was tested in three cabs to provide meaningful test results even if a few cabs fell out with mechanical problems or because of accidents. (Six of the 75 engines did, in fact, have problems, none apparently related to the oil's performance.) For a detailed description of our test procedures, see "Testing in the Big Apple," page 12.

Our shoppers all across the country bought hundreds of quart containers of oil. Some brands had slightly different formulations in different areas, but all the oils included a full package of additives.

The independent lab helped us identify the most representative formulations of each brand. Our engineers transferred containers of that oil to coded 55-gallon drums and hauled them to the fleet garage for testing.

Ideally, oil should be thin enough to flow easily when the engine is cold and remain thick enough to protect the engine when it's hot. The lab analyses of each oil's viscosity characteristics ---- its ability to flow ---- indicate that motor oils have improved since 1987, when we last tested them. This time, far fewer test samples failed to meet the viscosity standards for their grade ---- and those were typically outside the limits by only a slight amount. No brand stood out as having a significant problem.

We tested oils of the two most commonly recommended viscosity grades - ---- 10W-30 and 5W-30. Automakers specify grades according to the temperature range expected over the oil-change period. The lower the number, the thinner the oil and the more easily it flows.

In 5W-30 oil, for example, the two numbers mean it's a "multiviscosity" or "multigrade" oil that's effective over a range of temperatures. The first number, 5, is an index that refers to how the oil flows at low temperatures. The second number, 30, refers to how it flows at high temperatures. The W designation means the oil can be used in winter.

A popular belief is that 5W-30 oils, despite their designation, are too thin to protect vital engine parts when they get hot. However, one of our laboratory tests measured the viscosity of oils under high-temperature, high-stress conditions and found essentially no difference between 5W-30 oils and their 10W-30 brand mates. But at low temperatures, the 5W-30 oil flowed more easily.

Viscosity grade is important, so be careful. Recommendations vary with the make, engine, and model year of the car, so check your owner's manual and ask the mechanic for the proper grade of oil.

Of the 20 oils we tested, nine were conventional 10W-30 oils, and eight were 5W-30. We also tested two synthetic oils, Mobil 1 and Pennzoil Performax, and one synthetic-and-conventional blend, Valvoline Dura-Blend; all three were 10W-30 oils.

No Brand Performed Best
If you've been loyal to one brand, you may be surprised to learn that every oil we tested was good at doing what motor oil is supposed to do. More extensive tests, under other driving conditions, might have revealed minor differences. But thorough statistical analysis of our data showed no brand ---- not even the expensive synthetics ---- to be meaningfully better or worse in our tests.

After each engine ran about 60,000 miles (and through 10 months of seasonal changes), we disassembled it and measured the wear on the camshaft, valvefters, and connecting-rod bearings. We used a tool precise to within 0.00001 inch to measure wear on the key surfaces of the camshaft, and a tool precise to within 0.0001 inch on the valve lifters. The combined wear for both parts averaged only 0.0026 inch, about the thickness of this page. Generally, we noted as much variation between engines using the same oil as between those using different oils. Even the engines with the most wear didn't reach a level where we could detect operational problems.

We measured wear on connectingrod bearings by weighing them to the nearest 0.0001 gram. Wear on the key surface of each bearing averaged 0.240 gram ---- about the weight of seven staples. Again, all the tested oils provided adequate protection.

Our engineers also used industry methods to evaluate sludge and varnish deposits in the engine. Sludge is a mucky sediment that can prevent oil from circulating freely and make the engine run hotter. Varnish is a hard deposit that would remain on engine parts if you wiped off the sludge. It can make moving parts stick.

All the oils proved excellent at preventing sludge. At least part of the reason may be that sludge is more apt to form during cold startups and short trips, and the cabs were rarely out of service long enough for their engine to get cold. Even so, the accumulations in our engines were so light that we wouldn't expect sludge to be a problem with any of these oils under most conditions.

Variations in the buildup of varnish may have been due to differences in operating temperature and not to the oils. Some varnish deposits were heavy enough to lead to problems eventually, but no brand consistently produced more varnish than any other.

The bottom line. In our tests, brand didn't matter much as long as the oil carried the industry's starburst symbol (see "It's not just oil," page 14.) Beware of oils without the starburst; they may lack the full complement of additives needed to keep modern engines running reliably.

One distinction: According to the laboratory tests, Mobil 1 and Pennzoil Performax synthetics flow exceptionally easily at low temperatures ---- a condition our taxi tests didn't simulate effectively. They also had the highest viscosity under high-temperature, high-stress conditions, when a thick oil protects the engine. Thus, these oils may be a good choice for hard driving in extreme temperatures.

Note, too, that a few automakers recommend specific brands of motor oil in the owner's manual. You may need to follow those recommendations to keep a new car in warranty.

[Wayne 962]

Oil changes: How often?
The long-time mantra of auto mechanics has been to change your oil every 3000 miles. Most automakers recommend an oil change every 7500 miles (and a specific time interval) for "normal" driving, and every 3000 miles for "severe" driving ---- frequent trips of less than four or five miles, stop-and-go traffic, extended idling, towing a trailer, or dusty or extremely cold conditions. Many motorists' driving falls into one or more of those "severe" categories.

In our survey, almost two-thirds of our readers said they had their oil changed every 3000 miles or less. They may be following the thinking expressed by one of our staffers: "I have my oil changed every 3000 miles because that's what my father did, and all his cars lasted for many years."

To determine whether frequent oil changes really help, we changed the oil in three cabs every 3000 miles, using Pennzoil 10W-30. After 60,000 miles, we compared those engines with the engines from our base tests of the same oil, changed every 6000 miles. We saw no meaningful differences.

When Mobil 1 synthetic oil came out, Mobil presented it as an oil that, while expensive, could go 25,000 miles between changes. That claim is no longer being made. But Mobil 1 is still on the market, selling at a premium (along with pricey synthetic competitors from several other companies). And synthetic oil's residual reputation as a long-lasting product may still prompt some people to stretch their oil changes longer than the automaker recommends.

Determining whether synthetic oils last longer than conventional ones would require a separate test project. To try to get some indication, we put Mobil 1 synthetic into three cabs and changed their oil every 12,000 miles.

We intended to compare the results of these tests with those from the three taxicabs whose Mobil 1 was changed at our normal interval, every 6000 miles. Unfortunately, two of the three engines using the 12,000-mile interval developed problems. (We couldn't attribute those problems to the oil.) The third engine fared no worse than the three whose oil had been changed at 6000-mile intervals.

The bottom line. Modern motor oils needn't be changed as often as oils did years ago. More frequent oil changes won't hurt your car, but you could be spending money unnecessarily and adding to the nation's energy and oil-disposal problems.

Even in the severe driving conditions that a New York City taxi endures, we noted no benefit from changing the oil every 3000 miles rather than f your driving falls into the "normal" service category, changing the oil every 7500 miles (or at the automaker's suggested intervals) should certainly provide adequate protection. (We recommend changing the oil filter with each oil change.)

We don't recommend leaving any oil, synthetic or regular, in an engine for 12,000 miles, because accumulating contaminants ---- solids, acids, fuel, and water ---- could eventually harm the engine. What's more, stretching the oil-change interval may void the warranty on most new cars.

Testing Slick 50 and STP
We also tested Slick 50 and STP Engine Treatments and STP Oil Treatment, each in three cabs. (Slick 50 costs $17.79 per container; STP Engine Treatment has been discontinued.) All three boast that they reduce engine friction and wear.

The engine treatments are added with the oil (we used Pennzoil 10W-30). They claim they bond to engine parts and provide protection for 25,000 miles or more. We used each according to instructions.

The STP Oil Treatment is supposed to be added with each oil change. It comes in one formulation (black bottle, $4.32) for cars with up to 36,000 miles, another (blue bottle, $3.17) for cars that have more than 36,000 miles or are more than four years old. We used the first version for the first 36,000 miles, the second for the rest of the test ---- again, with Pennzoil 10W-30.

When we disassembled the engines and checked for wear and deposits, we found no discernible benefits from any of these products.

The bottom line: We see little reason why anyone using one of today's high-quality motor oils would need these engine/oil treatments. One notable effect of STP Oil Treatment was an increase in oil viscosity; it made our 10W-30 oil act more like a 15W-40, a grade not often recommended. In very cold weather, that might pose a risk of engine damage.

Recommendations
None of the tested oils proved better than the others in our tests. There may be small differences that our tests didn't reveal, but unless you typically drive under more severe conditions than a New York cab does, you won't go wrong if you shop strictly by price or availability. Buy the viscosity grade recommended in your owner's manual, and look for the starburst emblem. Even the expensive synthetics (typically, $3 or $4 a quart) worked no better than conventional motor oils in our taxi tests, but they're worth considering for extreme driving conditions ---- high ambient temperatures and high engine load or very cold temperatures.

On the basis of our test results, we think that the commonly recommended 3000-mile oil-change interval is conservative. For "normal" service, 7500-mile intervals (or the recommendation in your owner's manual) should be fine. Change the oil at least that often to protect your engine and maintain your warranty. Even for the severe service experiened by the taxis in our tests, a 6000-mile interval was adequate. But some severe service ---- frequent cold starts and short trips, dusty conditions, trailer towing ---- may require a shorter interval. Note, too, that special engines such as diesels and turbos, which we didn't test, may need more frequent oil changes.

We don't recommend stretching the change interval beyond the automaker's recommendations, no matter what oil you use. Engine combustion contaminants could eventually build up and harm engine parts.

As for STP Oil Treatment, STP Engine Treatment, and Slick 50 Engine Treatment, our advice is simple: If you use an oil with the starburst symbol, you don't need them.

(End - Ed.)


(reference to 'description of test procedures on page 12' shown below - Ed.)

Testing in the Big Apple
New York City taxicabs played a key role in our massive test project to evaluate motor oils. For consistency, we used only 1992-93 Chevrolet Caprice cabs. Each received a precisely rebuilt 4.3-liter V6 at the beginning of its 60,000-mile test. We started with six rebuilt engines; after each engine was installed in a cab, the six engines that were removed were rebuilt and installed in six other cabs ---- and so on. Using that rotation, we monitored 75 cabs over 4.5 million miles of driving in New York City and its environs. Each oil was tested in three engines.

A local shop completely machined each engine block and crankshaft, rebuilt the cylinder heads, and installed new bearings, pistons, rings, seals, gaskets, and oil pump. Though the engines originally had roller lifters and camshafts, a design that reduces friction, we installed conventional sliding lifters and camshafts to accelerate wear.

Before the engines were assembled, we measured or weighed the parts most likely to show wear if the oil wasn't doing its job ---- the camshafts, valve lifters, and connecting-rod bearings. Each cab went through a break-in procedure before hitting the road. During testing, two engine timers measured the time the engine was running and the time it was in gear.

Over the next 22 months, our engineers paid more than 100 calls ---- usually without notice ---- on the fleet garage. They dropped off test oil and picked up used-oil samples for ongoing analysis. They also made sure that oil was being added to the engines when necessary and changed as scheduled.

After each 60,000-mile test, we remeasured the key engine parts. We also examined combustion-chamber deposits, the color of the valves, scoring of cylinder walls, and valvedeck deposits for any sign of engine problems.

(reference to 'description of standards and symbols on page 14' shown below - Ed.)

It's not just oil
Certainly, motor oil is slippery. That's what helps protect an engine's moving parts. But motor oil does much more than lubricate. It helps cool the engine, keep it clean, prevent corrosion, and reduce friction to improve fuel economy To do all that refiners blend in various additives, which account for 10 to 25 percent of the product you buy.

[Wayne 962]

The oil industry has devised a starburst symbol to certify that a particular motor oil meets the latest industry requirements for protection against deposits, wear, oxidation, and corrosion. The starburst on the label means the oil meets API (American Petroleum Institute) Service SH requirements-the latest most advanced formulation. (Service SH supplants SG the previous top category.) The CD designation on most of the oils we tested refers to diesel performance. The starburst also indicates that the oil passes ILSAC/GF-1 standards developed by the International Lubricant Standardization and Approval Committee, a U.S.-Japanese group. And it means the oil meets Energy Conserving II requirements---- it improves fuel economy by reducing engine friction. All the oils we tested carry the starburst-and all performed well in our test. But note that oils without that symbol may not perform as well.

(Below -Ed.) are some of the additives found in modern oils.

Viscosity-index improvers modify the oil so its viscosity is more consistent over a wide temperature range.

Antioxidants prevent the oil from thickening when it runs hot for extended periods.

Dispersants keep contaminants suspended so they don't form deposits in engine.

Detergents help prevent varnish and sludge on engine parts and neutralize acid formed in engine.

Rust and corrosion inhibitors protect metal parts from acids and water formed in engine.

Pour-point depressants help the oil flow in a cold engine, especially in cold weather.

Friction modifiers strengthen the oil film and prevent unlubricated contact between moving parts.

Foam inhibitors collapse the bubbles churned up by engine crankshaft. (Foam reduces lubricating effectiveness.)

Antiwear agents provide lubrication when oil is squeezed out from between moving engine parts.

Ratings & Recommendations
Shopping strategy
Discount stores are generally the least expensive place to buy oil. Look for sales and buy by price ---- but make sure the container has the starburst symbol.

Details (listed alphabetically)

All the tested oils performed well in our tests, and all claim to meet the latest (API-SH and ILSAC/GF-1) industry standards (see "It's not just oil," (above - Ed.)). Prices are the average for one quart, based on a national survey of discount stores.

5W-30 oils
Castrol GTX $1.21
Appears to use same formulation in all areas sampled. Graduated container.

Exxon Superflo
Price not available; not widely found in discount stores. Appears to use same formulation in all areas sampled. Graduated container with window.

Fire & Ice All-Season (Shell) * $0.93
Different formulations in Florida and New York. Graduated container with window.

Havoline Formula 3 (Texaco) $1.11
Appears to use same formulation in all areas sampled. Graduated container with window.

Mobil * $0.95 Appears to use same formulation in all areas sampled. Graduated container with window.

Pennzoil $1.16
Appears to use same formulation in all areas sampled. Graduated container.

Quaker State Deluxe * $1.20
Appears to use same formulation in all areas sampled. Graduated container with window. 10W-30 is called Super Blend.

Valvoline All-Climate $1.14
Different formulations in California and Texas. Graduated container with window.

10W-30 oils
Castol GTX $1.18
Appears to use same formulation in all areas sampled. Graduated container.

Exxon Superflo $1.13
Different formulation in Florida. Graduated container with window.

Fire & Ice All-Season (Shell) * $0.99
Appears to use same formulation in all areas sampled. Graduated container with window.

Havoline Formula 3 (Texaco) * $1.13
Different formulations in Illinois and Texas. Graduated container with window.

Kendall Superb 100 * $1.23
Different formulation in Florida. 5W-30 version not tested.

Mobil 1 synthetic $3.76
Low-temperature flow characteristics were better than most. Appears to use same formulation in all areas sampled. 5W-30 version not tested. Graduated container with window.

Mobil $0.95
Different formulation in New York. Graduated container with window.

Pennzoil $1.16
Appears to use same formulation in all areas sampled. Graduated container.

Pennzoil Performax synthetic $2.97
Low-temperature flow characteristics were better than most. No 5W-30 version. Appears to use the same formulation in all areas sampled.

Quaker State Super Blend * $1.20
Appears to use same formulation in all areas sampled. Graduated container with window. 5W-30 is called Deluxe.

Valvoline All-Climate $1.13
Different formulation in California. Graduated container with window.

Valvoline Semi-Synthetic DuraBlend conventionl/synthetic blend * $2.12
Appears to use same formulation in all areas sampled. Graduated container with window. No 5W-30 version. Flow characteristics were more like those of a conventional oil than those of a synthetic.

* - One or more samples differed from viscosity-grade requirement by a small amount.

[Emission]

Thanks for posting that Wayne, I remember reading that in CU when it came out.

The CU test was done with NYC Taxi's, the "worse-case scenario" for motor oil. I don't think a Porsche (owned by an enthusiast) is exactly an apples-to-apples comparison.

My logic:

The NYC taxi starts once in the AM and runs most of the day without stopping. All are automatic transmissions (at least I think they are) and V8 or V6 designs. I don't think they see much over 3000 RPM during the course of the day. Water cooled, engine oil probably sits about 200 F. for most of the day.

The enthusiast Porsche starts and stops quite often on the days it is driven. Sometimes, it sits for days on end without running (as moisture and contaminants eat away at engine internals). Nearly all are manual transmissions and flat-6's. When driven, the engine is warmed up then happily spun to 6000+ rpm. Air cooled, engine oil temps fluctuate between 170 - 250 F.

To me, the CU report makes sense for most US drivers out there (my wife included). I think your average Porsche enthusiast pushes their oil a bit harder.

I would like to have seen oil analysis - chemical breakdown information - and sludge reports from CU. Instead, they measured wear. As they pointed out, all oil is slippery!

[Jack Olsen]

That article is a good reality check.

However, like Emission, I think I actually do "drive under more severe conditions than a New York cab does." as some Pelicanites who have been in my passenger seat can attest.

[fireant911]

Very interesting article and I can easily predict that there will considerable responses to the well debated subject. I have always believed that as long as an individual changes their oil that there will be minimal, if any, differences in the acheived life of the engine based solely on the brand of oil. Personally, I use Mobil one for two reasons: the better thermal protection offered by synthetics and the increased flowability characterics at lower temperatures - maybe I am a victim of good advertising but the documentation of the latter characteristic is sufficient alone for me to continue to use Mobil 1 (plus I have 12 five quart containers reamaining under my workbench).

One area worthy of discussion is the driving behavior of the driver in relation to engine life. My father drove his vehicles for years doing a commute to Chattanooga, TN back to Flat Rock, AL everyday which was about 35 miles one way. It was doubtful that he ever drove faster than 60 mph but he always did the 30 second warmup of the engine before driving. His current mode of transportation at the time was lucky to have the oil changed annually. About half of the commute was interstate but the oil was black and syrupy once it was 'completed it's sentence' in the engine case. He purchased a Volvo new in 1965 and sold it many years later in great runing condition with over 200K miles and he boastfully claimed that he once after removing the drain plug and nothing came out that he had to take a screwdriver and poke through the hardened 'crap' at the bottom of the sump to remove the old oil. He bought a 1972 Datsun pickup truck and managed to put 250K on it before he sold that one with the same 'maintenance' schedule. A 1950's VW he an my mom bought out in California had mega- miles before it was sold and to my knowledge the engine had never been apart - he did start a fire underneath the engine one day in order to bring the oil temperature up to a point where the engine would actually turn over.

I easily see that there are different demands from simply a commuter vehicle to a high performance car. With so many 'flavors' of oil out there it is more of a rhetorical type question with no definitive answer.

[Wavey]

Thanks for the post Wayne. Good information and well worth considering. However, how many of the taxis were air/oil cooled? Obviously none, and that makes me wonder how relevant this is to our 911 engines. And the observation about Mobil 1's cold-temperature flow is significant. I'm sticking with my Mobil 1 15/50 @ 5K - cheap insurance.

[Jim Richards]

Good article Wayne. Thanks for posting it.

To Jack's point, it would be valuable to see an oil comparison test for the track environment.

[Todd Simpson]

For all that text, here's the most important part for me.

One distinction: According to the laboratory tests, Mobil 1 and Pennzoil Performax synthetics flow exceptionally easily at low temperatures ---- a condition our taxi tests didn't simulate effectively. They also had the highest viscosity under high-temperature, high-stress conditions, when a thick oil protects the engine. Thus, these oils may be a good choice for hard driving in extreme temperatures.

[Wavey]

Originally posted by Todsimpson
For all that text, here's the most important part for me.

Yes, that stood out for me too, but for a different reason. CRs "thick oil" comment makes me think they don't really understand the characteristics that make an oil perform well.

[SandyI]

So now we all know how the poorly maintained, low performance, water-cooled, poorly engineered, American V-8 taxi's in N.Y. consume oil.

How about a useful article on how different brands of gasoline affect high performance precision Porsche engines?

[randywebb]

They were V-6's not V-8's (and hence more highly stressed). There is no market to do this involved a test for 911's.

The critical part is: "Big-city cabs don't see many cold start-ups or long periods of highspeed driving in extreme heat."

CU is to be complimented for doing a controlled study. They know what makes for a real study or test and what is just chaff or unsupported anecdote. But their criteria are not ours.

The important thing to realize is that the term "severe" is not uni-variate. Things can be severe in different ways.

The ultimate answer to the oil question is very simple: use what PAG says to use in all its cars -- Mobil One. IF you are worried about leakage, then use a good, brand-name dino oil with an SF rating.

[Jack Olsen]

"use what PAG says to use in all its cars -- Mobil One."

I do. But does anyone know how much Mobile pays Porsche for the favor of this recommendation?

[speeder]

Originally posted by randywebb
They were V-6's not V-8's (and hence more highly stressed). .

FWIW, this is incorrect. ~98% of NYC cabs are Ford Crown Victorias, usually no more than 3-4 years old.

[Emission]

Originally posted by speeder
FWIW, this is incorrect. ~98% of NYC cabs are Ford Crown Victorias, usually no more than 3-4 years old.

I think he was referring to this from CU:

"For consistency, we used only 1992-93 Chevrolet Caprice cabs. Each received a precisely rebuilt 4.3-liter V6 at the beginning of its 60,000-mile test."

[geof33]

Interesting... and really, pretty much an obvious conclusion.

I use Mobil one because there is no doubt my motor runs cooler with it... I've tried other synths and GTX. On balance I run about 20deg cooler, seldom ever getting above the first tic on the gauge. I change my oil every 7500 or 6 months whichever comes first. Porsche recomends 15,000 and a year. I think this is a reasonably conservative interval.

Also, as confirmed by the article, Mobil 1 flows better when cold. Well, when I start up my car and it's 25 deg in my garage that is good to know... (duh)

Great read though... Thanks Wayne.

[Bill Verburg]

Wanna get really confused? Over on the Audi boards for the S4s there are so many certifications and and specificatios that I can't keep them straight.

It appears that only M1 0-40(maybe) and Motul fullfill all of the specs,

Read this fo example.



Personally i'l stick w/ M1 15-50 for the Porsche and M1 0-40 for the Audi, even though both are likely not needed.

[SandyI]

All I know is the last time I was in a NYC taxi, I spent the majority of the time going about 3 mph in traffic listening to my driver talk on his mobile phone in some unknown language. Why not study motor oil performance in squad cars in various police departments? Those cars are stressed to their limit under extreme circumstances.

[Noel]

Originally posted by Bill Verburg
Wanna get really confused? Over on the Audi boards for the S4s there are so many certifications and and specificatios that I can't keep them straight.

It appears that only M1 0-40(maybe) and Motul fullfill all of the specs,

Bill, I just got a letter from Audi for my A4 with the 1.8L Turbo engine and the only oil now recommended has to have a VW501 certification. Currently only Mobil 1 0W40 and Castrol Syntec 5W40 has this rating of the oils that are commonly available. No Dyno oils are now recommended. Apparently, there has been Oil Sludge buildup issues in these engines with other oils which has been killing turbos and causing the oil pressure lights to illuminate. Fortunately Mine has been on Mobil 1 5W30 or 0W40 most of its life and at 120K no problems...YET!

[azasadny]

Wayne,

Thanks for the info!