Shell Rotella oil

[Duke W.]

Re: Shell Rotella oil

I wrote my oil article initially for vintage Corvette owners, but later stated that it applies to any vintage spark ignition four-stroke automotive engine with SLIDING SURFACE VALVE TRAIN COMPONENTS!!!

It was not meant to be advice for modern engines of any kind!

I'm disappointed that some OEMs are not longer recommending API service categories, but have their own specs like GM's Dexos. It may be more about another revenue source rather than solid technical issues, since using the name requires a licensing fee.

For modern engines I can only recommend what the OEM recommends, at least during the warranty period. After that you can do what you please, but it should be based on solid and reliable sources, not Web forums or You-Tube videos and the like.

I'm not sure if SJ is a current API category, and I believe using "obsolete" categories is a violation of API licensing agreements, but you can find out by downloading the current oil spec chart from www.api.com and reading the API 1509 document and appendices.


Duke

[Duke W.]

Re: Shell Rotella oil

So since Ford claims their new spec oil offers better wear resistance than CK-4 are you going to start using it in your vintage engines?

I don't recall seeing any C-category oils than don't include an S-category as a second rating. Some may list older C-category specs, but I think most are now simply CK-4/SN. And as I previously said, according to the API 1509 licensing document, secondary categories are optional.

Duke

[Timothy B.]

Re: Shell Rotella oil

Duke, I have been thinking about using the CK-4/SN 15W-40 in my every day driver cars also, I am not sure about all this new labeling stating synthetic blend in the Walmart 10W30 conventional oil.

I heard Tractor supply is also a source for oil but have not bought from them, I usually just go to Walmart.

[William F.]

Re: Shell Rotella oil

Duke et al
The label of the current Rotella T T4 oil says "heavy duty diesel oil" and is CK-4 only, no S secondary rating and says meets Ford as well as other diesel oil warranty specs. It's what I use. You're not saying seek out an oil that has an S secondary rating, are you?

[Duke W.]

Re: Shell Rotella oil

If your "every day driver cars" have "roller everything" valvetrains, then stick with S-category or whatever the OEM recommends.

Duke

[Duke W.]

Re: Shell Rotella oil

Duke et al
You're not saying seek out an oil that has an S secondary rating, are you?

No, I'm indifferent to secondary ratings. The primary rating, which is the FIRST listed rating is all I care about.

Duke

[William F.]

Re: Shell Rotella oil

But I believe in your previous explanation about ratings, A dual C and and S rating would have to have less P due to catalytic converter concerns than an oil with a strictly C rating. Correct? Probably reason doesn't recommend a combination c and S rating for their diesel engines.

[Duke W.]

Re: Shell Rotella oil

Prior to the SL rating most S-category oils were also rated for the then current C-category, and the choice of primary category was more of a marketing rather than technical consideration. For example, Chevron has spent decades building it's Delo brand for diesel engines, and many brands target gasoline engines even though they were also suitable for diesels, but that was then. These oils had no P limitation, and most had P concentrations of about 1200 ppm. SL imposed a 1000 ppm limit, which dropped to 800 for SM, and current SN is the same.

I can't say for sure what secondary ratings C-category oils typically had prior to SL, because I bought S-category. I wasn't until the P limitation of SL that I started using C-category and recommending it to other vintage car owners with sliding surfaces in the engine's valve train.

The first C-category P limitation came with CJ-4, 1200 ppm, and it's the same with current CK-4, but some are much less due to new Boron based anti-wear additives. This makes it plain stupid to buy engine oil based on P or Zn concentration as some do. The C-category API test suite is more rigorous and comprehensive than any amateur can conjure up. I costs millions of dollars for all the lab and field tests, and it covers way more than just wear protection.

The place to start researching for your own benefit is www.api.org, not bubba on some oil blog or You-Tube.

Duke

P.S. The USA is coming apart at the seams, and a madman is threatening to use nuclear weapons. We all ought to be worrying about bigger things than what "brand" of engine oil we feed out cars.

EOF

[Mark E.]

Re: Shell Rotella oil

After reading all of these posts by folks with an incredible level of knowledge about this topic, I have a question: What's the motivation to use diesel oil instead of oil for spark engines that contain required levels of P and Zn? Is it cost? Is it a belief diesel oils are superior in some way? Something else?

This isn't meant to be flippant or judgmental, I just want to understand the motivation.

[Joe L.]

Re: Shell Rotella oil

After reading all of these posts by folks with an incredible level of knowledge about this topic, I have a question: What's the motivation to use diesel oil instead of oil for spark engines that contain required levels of P and Zn? Is it cost? Is it a belief diesel oils are superior in some way? Something else?

This isn't meant to be flippant or judgmental, I just want to understand the motivation.

Mark------

I believe the whole issue is focused on the lowered levels of zinc and phosphorous in modern spark ignition engine oils. These have been progressively lowered in order to protect catalytic converters and other emissions-related systems. Diesel spec oils do not have to be concerned with catalytic converter protection issues and have other lubrication requirements. It is, thus, considered by some that the diesel oils are more akin to the requirements of older spark ignition engines which have no catalytic converter issues to contend with and have sliding contact surfaces. Principally, this involves flat tappet cams and lifters.

If I had an older engine with flat tappet cam and lifters I'd probably use a diesel-spec oil but I would want one with a dual diesel/spark ignition rating. Fortunately, I have no such engines. I have 4 vehicles including 2 Corvettes. ALL have hydraulic roller cams, including my "ZL-1" and original 1969 small block. I would not have it any other way. I have many original GM Corvette camshafts and lifters [none for sale] but I'd NEVER use one. Hydraulic roller cams can be had which deliver near original performance (or, greater if one so-wishes). They're the "ultimate" set-up for any original flat tappet engine.

So, I use SN full synthetic 5W-30 or 10W-30 in all my engines. Keeps things simple.

[Duke W.]

Re: Shell Rotella oil

After reading all of these posts by folks with an incredible level of knowledge about this topic, I have a question: What's the motivation to use diesel oil instead of oil for spark engines that contain required levels of P and Zn? Is it cost? Is it a belief diesel oils are superior in some way? Something else?

This isn't meant to be flippant or judgmental, I just want to understand the motivation.

Go to the "sticky" section at the top of the TDB home page and open the second from the bottom link - Restoration Documents.

Go down the keyword list until you get to OIL, and download and read the third OIL listing - "Engine Oil for vintage Corvettes"

The article will provide you with a thorough education on how to select engine oils for ANY engine including vintage engines with sliding surface valve train components.

You should also review the entire list as there are many articles than you may find interesting.

Duke