"Speedtalk" oil article

[William F.]

Duke et. al.
Trying to help a friend, new to vintage car hobby, with oil choice for his "69 375 hp 396 Chevelle by recommending a diesel oil with adequate ZDDP. He sends me an article saying this is all bull and "tests" verify modern nondiesel oils are superior even for flat tappets. Would like for you to read it and comment, please. Site is http://speedtalk.com/forum/viewtopic.php?f=1&t=32279.
Thanks,
William Ford
'67 L79
'67 L36

[Bruce B.]

Re: "Speedtalk" oil article

Interesting article.

It will be interesting to see what the NCRS "experts" have to say.

[Clem Z.]

Re: "Speedtalk" oil article

all i know for sure is back in the 70s i build a BBC racing engine for a short track racer. in 2 nights of racing the engine was completely worn out,cam block everything that ran in oil. i had filled the crankcase with "D-A speed sport" oil before delivery. i did not know this but the owner who was into off road heavy equipment had drained out the speed sport oil and put in series 3 diesel because he said if it was good enough for caterpillar engine it should be go enough for a chevy. i fired the engine at his place of business and did all the normal things done at a engine break in. 2 races later he called and said the engine sounded bad. so went over and took a look. the valve lash was way loose and the timing was way off. we pulled the engine and i took it apart and i had never seen so much wear on everything in the engine. that is when i found out about the series 3 diesel oil so i called my friends over at the gulf research labs here in pittsburgh and they told me that you should never use and diesel engine oil in any type of high RPM engine. they told me that cat engine run at 2000 RPMs and race engine runs at 7000 RPM and diesel engine was not formulated to be used at high RPMs. they sent me a letter stating this and the engine owner ended up eating the cost of a new race engine

[William F.]

Re: "Speedtalk" oil article

Clem,
Aren't you clouding the issue by comparing apples (diesel#3 oil) to oranges (Rotella T type oil)? My bottle of Rotella T which I have before me meets C(compression-diesel)J-4 specs as well as S(spark-gasoline)M specs-current high (highest?) specs for gasoline engines.Should be best of both worlds for engines with sliding friction-flat tappets, etc.,as Duke's oft quoted article states, shouldn't it?Don't know anything about diesel #3, must be a different animal. Help us out Duke and others who have factual knowledge on subject.

[Clem Z.]

Re: "Speedtalk" oil article

Clem,
Aren't you clouding the issue by comparing apples (diesel#3 oil) to oranges (Rotella T type oil)? My bottle of Rotella T which I have before me meets C(compression-diesel)J-4 specs as well as S(spark-gasoline)M specs-current high (highest?) specs for gasoline engines.Should be best of both worlds for engines with sliding friction-flat tappets, etc.,as Duke's oft quoted article states, shouldn't it?Don't know anything about diesel #3, must be a different animal. Help us out Duke and others who have factual knowledge on subject.

all i was pointing out that diesel oil may not be formulated for high RPM engines.

[Duke W.]

Re: "Speedtalk" oil article

Did you give him a copy of the NCRS oil article and ask him to make his own decision?

If not, do so and get his comments.

Regarding Clem's remarks: oil formulations, both blending stocks and additives have changed substantially since the seventies, and back then there were a lot of two-stroke diesels that used a different oil formulation than four-stroke diesles/gasoline engines. I have no idea what "series 3" diesel engine oil is - maybe it was a two-stroke diesel engine formulation, and I doubt if you could buy it today.

Also, what works or doesn't work for racing engines isn't necessarily applicable to road engines, either then or now.

Some claim that modern diesel engine oils foam excessively. But modern four-stroke diesels all have turbochargers spinning at 20,000 RPM, which tends to foam oil, so modern diesel engine oils have plenty of anti-foaming additive.

Duke

[William F.]

Re: "Speedtalk" oil article

Thanks Duke. Yes It's my plan to give him a copy of the article. I think he's decided to use Rotella T like I do and have done for years. Still, what's this about "diesel#3" and the old Gulf Oil co. saying "diesel oils are for high rpm?" Don't think this applies to CJ-4. Please comment

[Clem Z.]

Re: "Speedtalk" oil article

*** The higher the psi result, the higher the “Load carrying capacity/Film strength”, and the better the oil is at preventing wear. most all the diesel oils in the tests above came in lower number than the gasoline engine oils.

[Duke W.]

Re: "Speedtalk" oil article

Film strength is only important in boundary lubrication situations. In an IC engine, hydrodynamic lubrication is the case 99.9999 percent of the time.

It is well documented in many studies that, on average, 80 percent of automotive engine wear in typical daily service occurs during cold start and warm-up, though I am not aware of any studies that have shown any difference in wear using oils that cover the typical film stength range of commercial engine oils.

That's why I tell people that the worst thing you can do to your engine is a cold start!

In the referenced article, the author evaluates oil purely on the basis of film stength. He obviously doesn't understand how lubrication inside and IC engine works, and I seriously doubt that he understands the difference between boundary and hydrodynamic lubrication.

Do you, the reader, understand? It's in the NCRS oil article.

Duke

[Clem Z.]

Re: "Speedtalk" oil article

Film strength is only important in boundary lubrication situations. In an IC engine, hydrodynamic lubrication is the case 99.9999 percent of the time.

It is well documented in many studies that, on average, 80 percent of automotive engine wear in typical daily service occurs during cold start and warm-up, though I am not aware of any studies that have shown any difference in wear using oils that cover the typical film stength range of commercial engine oils.

That's why I tell people that the worst thing you can do to your engine is a cold start!

In the referenced article, the author evaluates oil purely on the basis of film stength. He obviously doesn't understand how lubrication inside and IC engine works, and I seriously doubt that he understands the difference between boundary and hydrodynamic lubrication.

Do you, the reader, understand? It's in the NCRS oil article.

Duke

what about cam and lifter interface,what is that as that seems to be where the whole problem started ??

[Duke W.]

Re: "Speedtalk" oil article

Hydrodynamic lubrication is a function of film thickness, film strength, and relative velocity between the two surfaces, and by far relative velocity is the biggest variable when you look at the range of cranking speed to redline, which is on the order of 30:1. Hydrodyaminic pressure in a typical engine at high speed is on the order of several thousand psi, which is sufficient to keep the two surfaces from actually touching. They are almost always separated by a thin film of oil.

Though the cam lifter interface only receives splash oil, it's usually enough to create a sufficiently thick film to allow hydrodynamic lubrication. The one exception is probably cranking.

I can't comment on the specific case you cited because I don't know anything about the oil, but racing engines typically have much higher valve spring force, and wiping out cam lobes is not uncommon. Then the debris in the oil rapidly wears everything else.

Of all the various requirements/tests required to achieve API certification, I'm not aware of any for film strength. The wear tests are done on operating engines.

Duke