ACEA A3/B4, ACEA C3, MB 229.50, 229.52 - Do any of these specs have a seal treatment requirement for the oild to prevent oil leaks in older cars?

[svenson]

If you want proof just look at BMW. Compared to the population they leak oil all the time even within warranty. If euro oils were so good at stopping leaks why do BMW's still leak? BMW uses Viton and Silicone for some of their gaskets.

i was't critical about this..euro vs other oils..what i really meant, was a question. what is IN some oils like m1 0w40 that seals oil leaks but other oils can't ..thanks for the answer! noted what you answered!