Oil viscosity - more difference than I would have thought

[theholycow]

If manufacturers were specifying insufficient oil, wouldn't engines commonly be failing prematurely from lack of lubrication?

[bowtieguy]

not likely, especially soon or immediate evidence of such. i wonder how much engine life is SHORTENED by using 20 weight in warm climates, excessive idling, daily a/c usage etc?

shortened or premature is relative to be sure. 100k? 200k? 300k? what is fully mature?

[slurp812]

Originally Posted by bowtieguy

not likely, especially soon or immediate evidence of such. i wonder how much engine life is SHORTENED by using 20 weight in warm climates, excessive idling, daily a/c usage etc?

shortened or premature is relative to be sure. 100k? 200k? 300k? what is fully mature?

We shall see. I run 5-20 all the time in my car, 125,000 and counting. Still runs like new...