Ultimate Motor Oil Thread or Why we hate CJ4/SM oils

[tholman]

Is it a myth that air cooled engines should use a straight weight oil and not a multi grade engine oil. I dont know where but I have always thought that a straight weight was the best for air cooled. Can somebody give an explanation

[afterburn 549]

I am going to guess it comes from a time when there was NO such thing as 20/50 .I think it hit the market late 70s.
I put it in my Harley when every one said t would blow up (At that time Harley recomended streight 50 wt!)
I never blew, and history shows all is well with 20 / 50 even in P cars

[DPDISXR4Ti]

Originally Posted by Tincanguy

Been using Shell Rotella T, 15-40 and its predecessors for years.

Yep, me too for my '86. Actually, I'm not terribly brand loyal to Shell - with as tight as the specs have gotten, any of the API CJ-4 15W-40 oils are essentially interchangeable. Lately, I've been using Motorcraft's version since it comes in a 5 qt bottle vs. 4 qt that all the other CJ-4 oils are packaged in.

[KNS]

The "Straight Weight" must be an old recommendation. When I was living in Socal in the mid '80s, there was a VW/Porsche garage (Foreign Motors in Temple City) that suggested I use Castrol straight 30 in my '68 VW.

I can't imagine they would still say that now, I think that shop is just Honda-Toyota these days.

[db_cooper]

Rotella T was the factory fill oil on new 911s back in the day..it was the reason they had a "Shell" sticker on them when new. Nothing exotic..good old fashioned HDEO oil.

Still use Rotella...great oil.

[HarryD]

Originally Posted by tholman

Is it a myth that air cooled engines should use a straight weight oil and not a multi grade engine oil. I dont know where but I have always thought that a straight weight was the best for air cooled. Can somebody give an explanation

tholman:

Back in the day, single weight motor oil may have been the way to go, but as of 1984, Porsche moved clearly to the 20th century with the use of multigrade oils. See below for a page from the owners manual.

Originally Posted by 84_Carrera

This is from my '84 911's owner's manual.



I did 20/50 3-seasons, and 10/40 in the winter... noticing pretty normal engine oil temps with 10/40 in the winter, and easier cold turn-overs.

Use at your own discretion.

[richardlw]

Straight weight oils are stuck in the minds of old-timers who can't change their thinking. A 10W-30 will consume less oil than a 30. It will also have more HP.

I touch briefly on that in my oil paper (just updated)
Selection of the right oil

[SRT356/911]

I'm and old timer and I use to use straight weight back in the 60's. Most Porsche folks are pretty adept at following the changes in technologies.

We even know how to use a mouse along with our computers.

[trentwat]

Originally Posted by Steve@Rennsport

FWIW,.........

JMHO, but there are two MUCH better Porsche-approved alternatives to Mobil 1 0w-40...I won't put M1 0w-40 in anything.

Funny thing...PCA's August '11 Porsche Panorama has a "Tech Q&A" regarding oils. The question is related to oil for a 2001 Boxster. The Respondee states, "The recommended oil is Mobil 1 in all Porsche cars produced from 1984 and up. The two approved oils would be 0W/40 or 5W/40".

Marketing? Partner promotion & relationship management? Technical differences? What gives? Pontification by webbies w/o REAL details? Official recommendation vs. optimal?

What gain does the PCA get out of touting the official Porsche recommendation? How can opinions on this board be so emphatically different?

[1990C4S]

Originally Posted by trentwat

Funny thing...PCA's August '11 Porsche Panorama has a "Tech Q&A" regarding oils. The question is related to oil for a 2001 Boxster. The Respondee states, "The recommended oil is Mobil 1 in all Porsche cars produced from 1984 and up. The two approved oils would be 0W/40 or 5W/40".

Marketing? Partner promotion & relationship management? Technical differences? What gives? Pontification by webbies w/o REAL details? Official recommendation vs. optimal?

What gain does the PCA get out of touting the official Porsche recommendation? How can opinions on this board be so emphatically different?

I don't know why anyone would be surprised to see the PCA (or any organization) recommend that you use the factory specified oil. There is an inherent risk in suggesting anything else. While individuals can proclaim other oils it's not the same for an organization.

There are thousands of oils, some people choose to research and choose what they think is the best compromise (all oils have some degree of compromise) and some prefer just to continue using 'what has always worked'. As long as there are different oils you will have different opinions....

[Steve@Rennsport]

Originally Posted by trentwat

Marketing? Partner promotion & relationship management? Technical differences? What gives? Pontification by webbies w/o REAL details? Official recommendation vs. optimal?

Porsche A.G. has a marketing agreement with Mobil so naturally, the factory and their dealerships recommend and stock that oil. There are other, Porsche-approved ones as well.

What gain does the PCA get out of touting the official Porsche recommendation? How can opinions on this board be so emphatically different?

I don't think PCA gains anything; they are simply repeating the factory's recommendations.

Opinions vary due to differing experiences,.......

[afterburn 549]

PCA ? they dont know anything anyway !
Pass the cheese pleasz

[RWebb]

well, I would not go that far

also, PCA was the "distribution center" for all sorts of esoteric Pooschey knowledge before the internet came along

[911pcars]

Originally Posted by RWebb

well, I would not go that far

also, PCA was the "distribution center" for all sorts of esoteric Pooschey knowledge before the internet came along

Yep. Don't know if their Up-Fixin' books and/or their contents are still available anywhere.

Sherwood

[Bill Verburg]

The first big oil controversy which occurred back in the early 70s was weather to use the new fangled 20w-50 oils that were coming out at the time, turns out they were fine but Castrol GTX did get a bad rep from this era. Prior to this straight 30 was the most commonly used oil.

Next oil controversy was the Dino vs Synthetic

latest is the ZDDP controversy. For long emissions systems life ZDDP levels have been reduced and for better economy lighter wt oils are used. ZDDP is an anti wear agent indicated for use where there are high loads, as in flat tappet cams.

Since modern cars don't have flat tappets and since the manufacturers are on the hook for 10 yr emissions warranties they will recommend modern low ZDDP low viscosity oils and it is just easy for them to back date this recommendation as they get to sell more parts when more engines wear out. Doesn't mean it's the best oif for your car.

Owners of older cars should avoid oil w/ the starburst seal on it as this is the sign of low ZDDP, low vis. oil

If you can get it there are several good 20w-50 or 15w-50 oils w/o the starburst seal that are available, my favorites are M! 15w-50 and Brad Penn 20w-50

[RWebb]

I now avoid anything with the word "Castrol" on it based on comments from Steve W.

Brad Penn, Swepco, and VR-1 are all known to be fine so I use Brad Penn in the 911, and VR-1 (cheaper) in the VW Vanagon.

[IROC]

Originally Posted by RWebb

Brad Penn, Swepco, and VR-1 are all known to be fine so I use Brad Penn in the 911, and VR-1 (cheaper) in the VW Vanagon.

I'm sure this is buried in this thread somewhere, but I just checked and VR1 has slightly more zinc and phosphorous than Brad Penn, although they are really close. I use VR1 because it is readily available around here.

[RWebb]

by "useful thoughts" you mean something other than the expert opinion of one of the top Porsche race car shops in the US I guess.

what exactly are you looking for??

[Eagledriver]

I've been using Blackstone labs for oil analysis on my airplane for a few years now. You could send them a virgin sample of the oil to test the zinc and phosphorus levels. Maybe run 5 quarts in your daily driver for a few months and then send in a sample. This would get you the oil information and the engine health of your daily driver.

-Andy

[RWebb]

Originally Posted by Black 993

Randy - I searched this thread and don't see that Steve or anyone else has weighed in on the Castrol 5W-50, which is new and being marketed to the older-car crowd. Maybe it's crap. Maybe it's fine. I don't know. I do know that it's available at my local auto parts store, as opposed to the oil you've listed. That's why I asked whether anyone knows if it's good oil for an air-cooled 911 engine. If you don't have an answer, please just move along. Thanks.

unfortunately there are many oil threads

I gave the answer I had. You might want to just move along and use whatever you want or go thru Charles Navarro's site or even do a search here.