Ron Burgundy
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- Jun 3, 2004
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I always understood oil had a dual purpose, the primary purpose is to keep metal parts separated while the secondary purpose is to cool the engine.
To keep parts separated requires a high film strength which relates to oil viscosity and the wear and friction-control package added to the base oil stock. But it’s all real complex chemistry as hydrodynamic and elastohydrodynamic lubrication and boundary layer conditions are all engineered. Synthetic oils have better film strength and thicker viscosity oils generally have better film strength.
To cool parts requires oil flow to carry the heat away, less flow makes allows the oil to get hotter while moving through the bearing and not enough flow will cook the oil within the bearing. The thicker the oil, the less the flow rate and the higher the oil pressure. And I’ve read that oil provides 30% of overall engine cooling so it’s not trivial.
As is, oil pressure and flow rate is a designed parameter within the engine. The the oil pump itself and the bearing clearances and tolerances along with other parts of the oil system within an engine all play a part. How much variation in oil viscosity an engine can safely tolerate before one or another engine design aspect is compromised I’ve got no idea.
Too thin or too thick can’t be good but the question is what is too thin or too thick. Other than GM’s engine designers, who really knows the engines viscosity tolerance. I suspect an oil temp and pressure gauge could be used to gain some indication if the engine isnt happy as different oil viscosities are tried, Oil analysis is another tool to get a handle on what’s occurring to the oil and the engine.
Me, as I’m still under a warranty, I’d get the best quality oil I can rationalise and change oil at 1/2 the factory service schedule for piece of mind. If I do a track day, I’d change the engine oil and brake fluid after the event, again for piece of mind.
Even with a quality full synthetic oil, what will kill the engine is frequent short trips and thus a buildup of combustion blow more and water resulting in acidic oil and sludge which ain't good...
For some owners, oil film strength issues may be the least of their problems
Hit the nail on the head
