Another Vegas Run and Oil Temps scared me

WarmAndSCSI

Bearing surfaces are made from an alloy of copper, tin, and lead (typically) or aluminum and silicon for modern Japanese engines like ours. None of these alloys can rust - they are non-ferrous. Our crankshafts are forged from high-grade stainless steel and do not readily rust unless left for the elements.

The only oil-lubricated component that can effectively rust in our engines are the 2nd compression rings, which are probably made from ductile cast iron. That will never happen, though, because the piston ring interfaces with the cast iron cylinder liners (which can also technically rust, but never do because of the wall-to-piston-ring interaction).

I think you're confusing oil oxidation at high temperatures with metal oxidation...

Sludge usually occurs due to water or other contaminants built up in the oil - it forms at low temperatures, not high. It's varnish that forms at high oil temperatures, and that can usually be witnessed by simply popping a valve cover and looking inside the cylinder head. Pretty apparent, and it should never be seen on an engine that has had regular oil changes with a good quality conventional (Castrol GTX comes to mind) or synthetic.

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