Over the weekend I spoke with the gentleman who installed the engine for the previous owner. He has been restoring cars professionally about 30 years. He said the shop he works for (very high end restorations) is recommending using Shell Rotella instead of regular or synthetic oil because it seems to have a better chemical makeup.

Any thoughts.....or what is the oil of preference?

81 350 crate motor with slightly modified cam.

 

Valvoline VR1 20 50
Amsoil Zrod
Mobil 1 15/40 racing
Kendall GT racing
All have decent zinc levels, believe moreso than the Rotella. Heard they took most of it out

Dont think theres any best one take your pic

 

He likes Rotella because it still has zinc in it to help lube the cam lobes of older engines. Not a bad idea if you have high valve spring pressure.

 

False, this has been thrashed to death.

 

^

They did have a SLIGHT reduction a while back, like late 200X, but still average over 1000ppm in zinc last I checked. Been a while since I checked but have not heard other wise.

The 5w40 Syn Rotella is a good all round oil. Flows well at colder temps but still has Zinc and also high temp protection.


Heres a Virgin Rotella 5w40 sample (shows over 1200 in zinc)
http://www.bobistheoilguy.com/forums...92#Post2330292

 

There is plenty of ZDDP in the above oils. The recommended viscocity for your car is 10W-40 or 10W-30. Higher oil pressure does not meen better protection. Film strength it what protects the metal parts from contacting each other. Synthetics have 5 to 10 times the film strength of a conventional oil the same weight. CJ rated (diesel) oils are limited by that designation to 1200 PPM phoshorous Max which is the part of the ZDDP molecule that protects flat tappet cams (most are considerably less). They also contain elevated amounts of detergents and dispersants to fight soot buildup. The problem is these additives compete for the same space on your lobes and lifters. The detergents reduce the effectiveness of the ZDDP.

http://www.joegibbsdriven.com/traini...detergent.html

All the oils above have higher levels of ZDDP. Racing oils have minimal detergent. They are designed for very frequent changes <500 miles. The Amsoil Z-rod is specificly designed for flat tappet gasoline engines that are stored for the winter and is available in a 10W-30. It has the correct type and amount of detergent levels, ZDDP, additive package and correct viscocity for your engine to run the entire season with yearly oil changes in the spring when you remove your car from storage.

 

Good grief, folks - we have a sticky for this...

http://forums.corvetteforum.com/c3-t...ppet-oils.html

 

Information is wrong in it, like the Rotella.
"Shell Rotella T is SM - meaning no more than 800 PPM"

See my link above to show it still has 1200ppm from the bottle.

 

I don't reference Rotella in the sticky at all. I can't speak to posts on the sticky.

VOA tests have showed varying ZDDP levels depending on the lab and the person sampling. Shell claims 1,000 PPM ZDDP.

Regardless, Rotella is exempt from SM by grade - as clearly detailed in the post if you took the time to read it

Again, we don't need to revisit this - it's all in the sticky, including for/against for diesel oils

 

1. I agree with this statement.

2. This is simply "NOT" true. Whoever provided that info apparently has never actually tested conventional oil film strength against synthetic oil film strength or they would know this is not correct.

I recently purchased an oil film strength tester to do my own testing. That way I would know for sure that the results were not faked to promote a certain oil. I'll be testing probably 25 to 30 different oils over time.

This past weekend I began my testing, after developing a repeatable and accurate testing methodology to follow. I also heated all the oils to 230*F so that all testing would reflect oil temperature in a real running engine. Because all of this type of testing I've seen up to now, has been at room temperature, or at 100*F (not *C).

Here are my results so far:

The results below, indicate the psi that the oil was supporting at the conclusion of its test. And of course “the Higher the psi, the Better the oil is”, for preventing wear. I’ve only just begun actual testing to record, and this is what I have so far:

1. Royal Purple 5W30 API SN (the latest spec), full synthetic oil = 95,975 psi

2. Castrol 5W30 Edge with Titanium API SN, full synthetic oil = 93,319 psi (2.8% lower than RP above)

3. Castrol 5W30 GTX API SM, conventional oil = 63,845 psi (33% lower than RP above)

So, here you can see that the Royal Purple's film strength is only 1.5 times that of the conventional GTX.

And Edge's film strength is only 1.46 times that of the conventional GTX.

That's a long ways from 5 to 10 times higher film strength.

 

I happen to agree with your engine installer. I have been using Shell Rotella 15W 40 for many years in all of my older, flat tappet motor Corvettes for years with no issues whatsoever. You won't get a consensus on this. I can only offer my personal observations and those of many that I know that have used it without any issues.

 

billla First introduced this link into this thread-discussion; referencing his oil sticky thread.
billla introduced his oil sticky thread into this thread.

several of us have fair or better recall:
I recall billla proclaimed the oil sticky was property of this forum which has final say-so but that it is his thread and that he decided how and when it would be edited/formatted/reedited/reformatted. I recall the very agenda of his oil sticky thread did change; at one time it did clearly if not prominently include Rotella within the list of flat tappet oils... but has since been reformatted ad nauseum.

I distinctly recall billla presided over many quotes/posts that did claim Rotella had a relatively low Zinc approx 800 ppm. With somewhat less confidence, I also recall billla did himself post similar data from someone's VOA data he'd likely captured elsewhere. Those "800 Zn Rotella" posts probably since edited/deleted but, nevertheless, those posts did exist.

Seems to me, by claiming oil sticky as his thread, then billla should also take credit (and discredit) for its content.

Rotella is/was referenced many times in the oil sticky thread and (for the time being) is also referenced on page 4 of the excellent NCRS article penned by Duke and linked into by billla. Seems, at least for the time being, Duke's post appears in billla's oil sticky thread at about page 25.

And yes, I do understand all thread & posts within this forum are ultimately property of Corvette Forum.

And yes, I do also like and use Rotella / diesel oils in sbc.

Seems to me, if someone (anyone) doesn't want to revisit something, then they should not bring that something into the discussion.

 

Sure you will From the sticky:

Testing that showed the new oils would still have acceptable ZDDP for flat-tappet cams was done with very mild cam profiles and very low spring pressures. This is not what is found in even a mild performance engine, but may work - or at least appear to work - in older stock-type engines that don't see hard driving, have mild cams and tired valve springs or just see very few road miles

 

The motor in my 61 is a high performance 383 stroker with a flat tappet cam. I don't race it but I certainly don't drive it like a slug.

The 65 is a stock 327/350 11:1 compression
68 is a stock 427/390 10.25:1 compression.

Every time I drive them the secondaries are opened at least a couple of times. All I can say is I've driven many thousands of trouble free miles in all of them with no issues, so I think it MAY be working OK

 

Nice rides!

You're absolutely right - it MAY well be working great for you. I would offer however there is still a difference between those engines...and a modern cam with a steep ramp and stiff springs. Hence no "one size fits all" recommendation - but all covered in the sticky

Regardless, ultimately everyone needs to make up their own mind - which is why the sticky includes right at the top links to post for and against diesel oils as well as the rationale for why it's not included on the list.

If there's new information on any of this - I'm certainly open!

 

I did not make this up or invent this information. Look at the ninth paragraph down. My assumption was this statement was the result of verifyable laboratory testing. I guess it could be false advertising but I would think if it was the lawsuits would be flying.

http://www.searchforparts.com/import...ngine_life.php

"Film strength", refers to the amount of pressure required to force out a film of oil from between two pieces of flat metal. The higher the film strength, the more protection is provided to such parts as piston rings, timing chain, cams, lifters, and rocker arms ...wherever the lubricant is not under oil system pressure. Synthetics routinely exhibit a nominal film strength of well over 3,000 psi, while petroleum oils average somewhat less than 500 psi. The result is more lubricant protection between moving parts with synthetics."

 

HEY DIESEL OIL GUYS!!! READ THIS!!!

http://www.joegibbsdriven.com/traini...detergent.html

 

Enough gentleman.