Is 15w40 oil for diesel the same as regular oil?
 

I found some cheap Shell Triple protection 15w/40 motor oil for my 930, however, the label says 'for heavy duty diesel engines'. I have two separate questions:

1. Is 15w40 oil for diesel any different than 15w40 for non-diesel?

2. Any opinion on the quality of this oil? I have read all the posts of which brands people prefer, etc. I'm in the camp that says change the oil frequently, then you don't have to worry too much about getting the perfect oil.

The jugs/bottles say on the front. Heavy Duty Engine Oil. HDEO

Marketing is primarily for over the road trucks and the back of the jug will have several illustrations. It is used without complaint in motorcycles and 911s.

http://retropopplanet.files.wordpres...15w-40-oil.jpg

yep, that's it. Thanks

I use it in my BMW 135i because it doesn't breakdown under extreme heat as much as other oils so it would make sense for a turbo car or something along those lines.

Answers:

1. Yes, there are differences.

2. I'd read the oil thread before selecting this oil.

JR

Rotella T meets specification requirements for both diesel and gasoline engines.

I (along with others) have used in my 911 for years.

Jerry M
'78 SC

I run Rotella T in my 911 and have been happy with it.

There are significant differences but most/all of them work in your favor.

Hmmm, let's see. A diesel engine redlines at 4,000rpm max, most of them less than that. So I guess if you keep your Porsche engine below 4000 it would be ok?

I know this has been discussed extensively but I just frankly don't understand driving a Porsche then wanting to get cheap on the oil. Save $2 per qt over the well known brands that have a proven history in an aircooled Porsche engine and risk a $20K engine?

That reminds me, I still owe you a case of Brad Penn!

Back in the '80's and '90's, I used lots of Shell Rotella on non-turbo cars. Since then, other oils have come onto the market that I think are better for a turbo. And, I am not a fan of any oils that meet the API classifications of the last 10 years, or so.

I'd suggest reading the long-winded oil thread here, if you haven't already done so.

JR

The diesel oil thing perplexes me. I did a search on Kendall's website for their HP 20W50 racing and didn't find much. So just out of curiosity I did a vehicle application search. The oldest 911 it would let me select is a 1995 911. The oil recommendation that came up, Super D XA 15W40............. WTF????

Phillips 66 Lubricants: World-class products and services

years ago diesel engine oil and gas engine oil was different - thats not the case any more. Only in rare cases does a engine oil get formulated to meet the demands of a diesel engine (think large marine or locamotive).

They all use essentially the same add packs from one of 4 major additive companies. The only difference comes in the base oil technology and QA...

i use it in my bike as it has a wet clutch. if you pay attention you can snag gallon+ bottles on sale for under $11 (i currently have 5 in my garage). for the 911 i use valvoline vr-1 racing 20w50.

lots of porsche guys recommend swepco oils , gear oils . they were made for comercial heavy equipment,industrial use and over the road diesels . the same as most hdeo oils. the cars we have sitting in our garages dont get wet or dirty, oil changed more than needed. will hardly see the extremes of the use swepco lubricants and other hdeo oils were designed for.

The Kendall 15w40 meets the API service requirements for gasoline and diesel. The gasoline SN rating with the CJ-4 diesel rating. From the website:

Super-D XA meets or exceeds the requirements of: API Service CJ-4, CI-4 with CI-4 PLUS, CI-4, CH-4, SN.

The API rating will tell you. HDEO is the way to go. Look for Heavy Duty Engine Oil. Much more robust additive package than PCMO (Passenger Car Motor Oil)

There are those that believe that meeting the latest API requirements isn't a good thing for our engines.

That's why the oil thread came about...

JR

Agreed about the severe duty that diesel and commercial see. For typical street use I would think a good diesel oil with the right additive package would be plenty sufficient.

But how are we sure that those HDEOs can hold up to the abuse of racing or track driving? For me, i'm sticking with the lab tested oils that air cooled people have given their thumbs up on. Too risky to go cheap on oil and damage the engine. Already neck deep in rebuild #2 (way too soon after #1) and don't want to shoot myself in the other foot.

Mike at JB Racing in Florida put the Shell Rotella in my 3.0L engine we built to turn 7500 rpm. He builds and races lots of Porsche engines, I trust his advise.

Good point. So what's the spec for Rotella T 15w40? CJ-4/SM You can find the API specs pretty easy on the internet. Sure enough SN spec says maximum of 800ppm for Phosphorus. That's not good and a lot of folks talk about this...but there's a footnote on the limit.


So now we are back to looking at the CJ-4 limit for phosphorus which is 1200ppm. This is good. You can also find links to recent VOAs on Rotella T 15w40. Those show in excess of 1000ppm for ZDDP. The only way to know for sure is to buy a bottle and pay for your own VOA.

Oil specs changed. Oil got bad. People cried out. Market responded. There are more 'good' oils now than a couple of years ago. Oil is still changing. The only way you'll know for sure is to test what you are buying. Do your homework and you don't have to spend a fortune to get a quality oil.

FWIW I currently have Brad Penn 20w50 in my car and 12qts of Rotella T 15w40 on the shelf for the next oil change. Nobody has to live with my car but me.


-J