VCCA Home Forums GENERAL DISCUSSION General Discussions Engine oil ?

https://www.motortrend.com/how-to/diesel-oil-in-gasoline-engine/

Aand the best part is the 6 cylinder engines that mst club members have do not require an large amount of Zinc.

There's one section in the article that makes me question the credentials of Mr. Speed Jr.. The section saying the rotating assembly is turning while bathed in the oil in the crank case, thereby creating foam. I'm not an engineer but I wasn't aware that any rotating assembly in any engine is immersed in oil. I don't think the physics, angular momentum and law of inertia, would allow that practice to be successful. Perhaps it was just poorly worded to the point it leads a reader to make the assumption that he was trying to say that when he wasn't.

All good engine oil has Silicone added to prevent foaming.

I thought I recognized the name. Obviously he has some expertise with engine oils.

Lake Speed Jr.

I also am a little skeptical about the rotating components foaming the oil. In general engine designers try to avoid that for 2 reasons. One is the problems created by foaming oil. The other is that it consumes power. I can see where it is an issue in racing engines that do not use a dry sump oil system.

The need for zinc is one of those topics that can be discussed indefinitely with no conclusions.

There is one question I ask and never get a response. Does anyone have first hand knowledge of an engine failure due to the lower zinc levels in today’s oil?

An interesting article that the most informative point I found is to check with the engine manufacturer for the best results. Even amongst diesel engine manufacturers there are varying recommendations for lubricating oils and not all diesel oils are the same.

I can be your first response then although it may not be comparing apples to apples. Way back in the olden days of 2006 I was a parts guy for one of Toyota's first Sprint Cup teams. In racing we had a concept called the "infant mortality of parts". The concept being that parts either failed early in their "lifespan" or later after being run for a number of miles. We extensively tested individual parts and assembles such as engines, which we got straight from Toyota. We would determine the sweet spot for running a race within those two bands of high likelihood failure. We never ran a brand new part on an actual race day. When it came to engines, the engineers found that by adding GM EOS assembly lube to the oil to increase the zinc levels we could greatly widen the band of less failure likelihood. Unfortunately, GM EOS assembly lube was discontinued/reformulated in this timeframe. So me, being a lowly parts guy, was tasked with sourcing it from across the country. I called probably hundreds of dealerships looking for the stuff to add zinc to our oil.

Take it as you will. Coulda been other stuff in the formula that made a difference, the engineers were pretty adamant about it being the zinc.

Hi Tiny

As the oil emerges from the edge of a rotating bearing journal, you effectively have a rotating unit bathed in oil.
That oil can and does become foamy.
I've seen film footage of it happening.

Besides that, the rod dippers on old Chevs are bound to mix air into the oil as well, wouldn't they?

Also, many splash lubed engines (like old Kohlers etc) had rotating elements half immersed in the oil (sometimes even governor weights) as the main or sometimes only supply of oil to all other parts.

PS
Hope you don't take offense to what I posted, none was meant. :-)

Hi Primo

No offense meant here either,
but I think the author actually tried to make the point that comparing a racing engine with high valve lifts and high spring pressures running at much higher speeds to a production vehicle engine IS comparing apples to oranges.
I've used GM EOS in the past myself.
I am however now hesitant to use any ZDDP additive after having learned that higher isn't always better.
And it doesn't have to be a lot higher to actually do long term damage.

ZDDP at .06%, or .08%, or .10% is great.
At .14% things start to turn around.
At .20%, camshaft spalling will actually occur over time.

In a racing engine you would probably never see the long term results of ZDDP levels that are too high.
But in an old classic that may be around for decades to come, camshaft spalling isn't something I want to see.

PS
I asked my Mech Eng son if spalling due to high levels of ZDDP attacking the grain structure of the camshaft was possible.
He said yes, definitely.

A very interesting article that essentially corroborates what I have read from other tribologists.

I think one of the most important points made, and often overlooked, is that ZDDP is a SACRIFICIAL additive.
It binds to the metal when and where wear conditions warrant it.
The large bearing surfaces and low contact pressures of a Chev six won't provide those conditions to any great extent.
Therefore the ZDDP will be sacrificed at a very low rate, and somewhat lower initial levels won't necessarily result in excessively low levels at oil change time.
Keep in mind that some diesel engines are now recommending 250 or even 500 hour oil change intervals (as opposed to 100 hours years ago).
Think of the depletion that will be occurring there!

So, if you are still worried about ZDDP levels in today's oils, just change more often, before much depletion occurs.

Great discussion points. It is helping me determine if I need to do anything special with respect to an upcoming oil change in a new to me engine with a flat tappet camshaft.

The “experts” on forums for that engine make it seem like that engine will almost immediately self-destruct if you run an oil with “only” 600 ppm zinc. Yet if you dig deep enough you find that the real concern is high performance versions of that engine. By that I mean those engines running higher speeds and high valve spring loads on the flat tappets.

The “apples and oranges” comments here are very applicable.

With the latest API gasoline and diesel oil specs I definitely would be cautious about running diesel oil in a gasoline engine. The prior specs would allow an oil manufacturer to rate a given oil for both engines. Now the specs are such that as Lake Speed noted a given formulation most likely cannot achieve both ratings.

No offense taken. You don't have a rotating unit bathed in oil. "Bathed" in oil would have a rotating assembly partially or fully below the surface of the oil at all times during operation. Bury a crankshaft half way in a pool of oil and spin it up to automotive RPM and see how that goes. Hitting low viscosity water at 80 MPH is like hitting a solid surface. Now put higher viscosity oil and an object (rod journal counterweights for example) far in excess of 80 MPH slamming into the oil repeatedly. Not a recipe for long life. A rotating assembly fully submerged would be limited to very low RPM from the friction of trying to move all those "protrusions" through a highly viscous liquid. Not really conducive to traveling at speed.