Quote Originally Posted by howardc64 View Post
On shifting to synthetic, it can leak on higher mileage engines that haven't used it. This is because synthetic is good at cleaning out the gunk around the seals and sometimes the gunk is holding back a leak
Quote Originally Posted by Astro14 View Post
Howard - I've heard that about synthetic oil before - that it will cause leaks in higher mileage engines because it removes the gunk...
I believe this to be an old wives' (mechanics'?) tale, from the very early synthetics that were not entirely compatible with conventional oils.