Originally Posted By: SonofJoe
Put all of this together and you could logically conclude that over the decades the trend is one of worsening wear in real-life.
I dunno... The first engine I ever rebuilt 100% (bored .030, new pistons, etc.) back in 1985 was a '73 Chevy 350 engine with less than 150,000 miles on it.
.030" BARELY cleaned it up, the ridge was that deep (.012" each side). This engine was completely wore out before a rebuild. All new valve guides needed, too.
Fast forward 32 years, and I'm driving a F150 with a 4.6 and over 140,000 miles. Looking in the oil fill cap hole, the engine is spotless inside. It doesn't burn a drop of oil in 4,000 miles. It has been run on 5W-20 it's entire life.
I know these are JUST two examples, but I think the evidence is there to support the fact that it's NOT just the new oils, but new everything - new metallurgy, new manufacturing techniques, better engine management (EFI, knock sensors, etc.).
However, If I rebuild an engine from the early 70's today and run it on modern oils, will it last just as long? (using 10W-30, or 15W-40, etc. etc.)