negcamber

Could very well be true...I'm not really sure how much technology has changed for normal dino oils over the last 20 years. I assumed that oil companies would have put most of their R&D towards the synthetics and blends. Those have certainly been the oils heavily advertised other than the newer oils for high milage cars (which I would think are actually designed to "hide" leaks).

I can tell you my experience and the "conventional wisdom" says higher milage cars that have exclusively used natural oils have more sludge than ones that have primarily used synthetic, and switching to synthetic after that sludge has built up can lead to leaks.

Dunno...your experience may be different...I can just tell you what I've seen.

RACER

Like spitfire said, if an engine is leaking oil, it should be addressed no matter what type of motor oil is used.

Conventional motor oil may help restore compression on a high milage engine, as in aid the piston rings.

I used Mobil 1 5w-30 on a MY94 Del Sol VTEC that had 54k when I got it. The previous owner (1st owner) used conventional oil. I switched to Synthetic Motor oil right away. That car saw 8,200 rpm's every day during my ownership. That thing was fast for a 1.6 liter n/a machine.

When I sold it at 135k miles, it ran like a thoroughbred race horse

RACER

And it didn't burn any oil.