Best oil viscosity for our engines

[Frederick W.]

I've been reading a lot on the Corvette Forum as well as this board, and from Duke W., regarding the issue of ZDDP and sliding surface wear.

However, there is much less discussion of other issues of oil selection, in particular, viscosity ratings.

I found a very detailed mini "course" on motor oil posted originally on a Ferrari chat board by Dr. A.E. Haas whose undergraduate degree was in biochemistry, now a full time neurosurgeon and part time mechanic. Dr. Haas is apparently an expert of sorts on oil and has studied and published on the properties of oil viscosity. He refers extensively to SAE and ASTM and other authorities and apparently follows the presentations from their meetings.
Dr. Haas is an advocate of synthetic oil, but particularly an advocate of very "thin" oils at start up (ie. 0W-xx grades). He states that 90% of engine wear occurs at start up, and that the thinnest oils currently available (0W) are still to thick at startup (ie. more viscous than the 10 cS (centistokes) that would be ideal).

Here is a link to his tutorial:

http://www.ferrarichat.com/forum/faq.php?faq=haas_articles

I'd be interested in the thoughts of our engineering members on the points made in this tutorial. Reading it has made me strongly consider switching to a 0W or 5W-30-40 grade oil, from a 10W-30. The discussion of the relationship between pressure, flow, viscosity and temperatures as they relate to lubrication are points of interest as well.

[Michael W.]

Re: Best oil viscosity for our engines

Despite 90% of wearing occurring at start up, the use of old fashioned, outdated non-boutique oil types, lack of meticulous maintenance by owners, abuse during overly spirited operation, these engines frquently last 100-150-200,000 miles with barely a complaint.

What's to be gained?

[Dick W.]

Re: Best oil viscosity for our engines

These older engines were not designed to run 0W-30 oils in moderate temperatures. 10W30 has served millions of engines very well as has 30W, 15W40, etc. I tried to follow the good doctors rambling sometime ago. Me thinks he should stick to brain surgery and leave oil recommendations to API and the car manufacturers

[Domenic T.]

Re: Best oil viscosity for our engines

I don't buy the 90% wear happening at start up.
I do think those thinner oils wear our older engines out during running much faster as the noise level tests are higher in an engine with thinner oil.
It boils down to bearing clearance and the cushion the oil provides.
One could say that the thicker oil that remained on the bearings provides a better coushion at start up.
The newer engines have tighter clearances than the older designs and need that thin oil, not mine.
Again I think it depends on the piston to wall and bearing clearance.

DOM

[Dick W.]

Re: Best oil viscosity for our engines

I don't buy the 90% wear happening at start up.
I do think those thinner oils wear our older engines out during running much faster as the noise level tests are higher in an engine with thinner oil.
It boils down to bearing clearance and the cushion the oil provides.
One could say that the thicker oil that remained on the bearings provides a better coushion at start up.
The newer engines have tighter clearances than the older designs and need that thin oil, not mine.
Again I think it depends on the piston to wall and bearing clearance.

DOM

Domenic, I can agree with the 90% wear occuring at cold startup. We had a truck that ran 24/6, only shutting down to check oil or service. The truck ran 750k miles perfectly but had a radiator hose blow off. The engine manufacturer wanted to inspect the engine. ALL parts were within the accceptable wear range to reuse, with the exception of the piston rings. They were not acceptable because they had been hot and lost tension.

Start up is very hard on a cold engine. No oil pressure for a few moments, oil does not flow well cold, etc.

[Duke W.]

Re: Best oil viscosity for our engines

I can only hope that I never run across that doctor in a medical setting and get the same rambling, disorganized, convoluted, techno-babble diagnosis. This Web posting in particular seems to be brought up every few months.

It's very simple. Your original owner's manual has viscosity recommendations based on the lowest anticipated regularly occuring cold starts and the highest outside temperature it will see in service. Those recommendations are as valid today for vintage engines as they were when the engines were built.

Some of you guys spend WAAAAAAY too much time obsessing about engine oil, and it seems to be fed by well meaning, but amateur enthusiasts who over analyze ad nauseum.

Perhaps the good doctor's time would be better spent developing a "Theory of Everything" that can unite Einstein's General Theory of Relativity and Quantum Mechanics.

There have been several studies over the years published as technical papers and in technical journals stating that the vast majority of engine wear over the life of the engine occurs during cold start and warm up. We can argue over the percentage, but from what I have read, 80 percent is a good ballpark figure.

This is why using an oil with no more that the viscosity recommended by the manufacturer for the lowest regularly occuring anticipated cold start should be observed, but there is no proof that using a much lower viscosity is beneficial.

Also, during the first few minutes/miles of operation, the engine should be kept at low revs and light load. Drive it very gingerly to allow the engine and other lubricated mechanical systems to come up to temperature, and don't place high demands on them until they are fully warmed up.



Duke

[Donald L.]

Re: Best oil viscosity for our engines

Except for API CJ-4 or CI-4 oil, lower viscosity SM oils are limited to 800 ppm or less phos. the anti wear element in ZDDP.

[Larry T.]

Re: Best oil viscosity for our engines

oil does not flow well cold, etc.

Regarding oil viscosity, I live in the deep south, summers are around 100* plus, winters can get into the 30's. Should I be using different oils at different times of the year? If so, what should I be using?

[Duke W.]

Re: Best oil viscosity for our engines

There was some NCRS guy - some kind of retired engineer from the auto and aerospace industry - who wrote a paper about engine oil for vintage engines that was published in The Corvette Restorer circa 2008 and reprinted in a Jeep club online newsletter that listed the temperature range that 15W-40 CJ-4 is suitable for?

I think the lowest temperature he said it was okay for regularly occuring cold starts was something like 10-15 deg. F. I'm not sure, my memory is getting bad due to the onset of senility.

I think he may have also mentioned that CJ-4 is also availalbe in a 0W-40 in you like to start your vintage Corvette at sub-zero temperatures and drive it around in the snow and ice, but 0W-40 is about double the price because it is blended from more Group II and Group III base stocks to achieve the wider viscosity range and is therefore, considered to be "synthetic" even though that particular term has no definitive technical or legal definition.

Duke

[Dick W.]

Re: Best oil viscosity for our engines

Regarding oil viscosity, I live in the deep south, summers are around 100* plus, winters can get into the 30's. Should I be using different oils at different times of the year? If so, what should I be using?

Use what your owners manual recommends'

[Frederick W.]

Re: Best oil viscosity for our engines

Some of you guys spend WAAAAAAY too much time obsessing about engine oil
Duke

Ha! C'mon Duke, being a member of the NCRS obviously selects for obsessive and compulsive tendencies, so it shouldn't surprise you. Normal car guys don't worry about even 1% of the stuff we concern ourselves with. I'm sure they think we're quite odd.

In fact, I bet if we had to take a personality trait test, most of us would score very high on the obsessive axis.

Point taken, though.

Fred

[Domenic T.]

Re: Best oil viscosity for our engines

I can only hope that I never run across that doctor in a medical setting and get the same rambling, disorganized, convoluted, techno-babble diagnosis. This Web posting in particular seems to be brought up every few months.

It's very simple. Your original owner's manual has viscosity recommendations based on the lowest anticipated regularly occuring cold starts and the highest outside temperature it will see in service. Those recommendations are as valid today for vintage engines as they were when the engines were built.

Some of you guys spend WAAAAAAY too much time obsessing about engine oil, and it seems to be fed by well meaning, but amateur enthusiasts who over analyze ad nauseum.

Perhaps the good doctor's time would be better spent developing a "Theory of Everything" that can unite Einstein's General Theory of Relativity and Quantum Mechanics.

There have been several studies over the years published as technical papers and in technical journals stating that the vast majority of engine wear over the life of the engine occurs during cold start and warm up. We can argue over the percentage, but from what I have read, 80 percent is a good ballpark figure.

This is why using an oil with no more that the viscosity recommended by the manufacturer for the lowest regularly occuring anticipated cold start should be observed, but there is no proof that using a much lower viscosity is beneficial.

Also, during the first few minutes/miles of operation, the engine should be kept at low revs and light load. Drive it very gingerly to allow the engine and other lubricated mechanical systems to come up to temperature, and don't place high demands on them until they are fully warmed up.



Duke

Duke the only thing you forgot to say is that the oils today are also improved from what they used to be. Given that they are the same viscosity.

DOM

[Duke W.]

Re: Best oil viscosity for our engines

Perhaps you can expand on your statement.

Duke

[Duke W.]

Re: Best oil viscosity for our engines

Ha! C'mon Duke, being a member of the NCRS obviously selects for obsessive and compulsive tendencies, so it shouldn't surprise you. Normal car guys don't worry about even 1% of the stuff we concern ourselves with. I'm sure they think we're quite odd.

In fact, I bet if we had to take a personality trait test, most of us would score very high on the obsessive axis.

Point taken, though.

Fred

Sure, we're obsessive about things like originality, but this obsession with engine oil is pathological. It's noteworthy that none of these discussions arise from anything originally posted here. It's always when someone posts a link to another Web site with some seeping pile of b....t.

NCRS members should know better. They have the benefit of a better education on this issue - both through the Corvette Restorer and the TDB, which is why I am confounded by the continuing surfacing here of the old myths, misinformation, and junk science that polute most automotive discussions on the Web.

Duke

[Peter M.]

Re: Best oil viscosity for our engines

Duke - put Valvoline VR1 Racing oil in my 71 LT-1 because the web site said it had zddp/phosperous of .014/.13 which I now see your article says is ok but at outer bounds and not necessary to be that high. Also, it is 20w-50 synthetic oil which now makes me think weight was not a smart thing based on this thread for my engine either.
I also read that the racing oil might(?) have also been a bad choice because it does have the right detergents/additives/whatever but thought(likely incorrectly) that only mattered if you drove the car all the time as opposed to weekend toy like a 71.

Thoughts?

Thanks

Pete