[TRFanatic]

My 87 GN has had an oil leak for awhile now, I usually have drops of oil on the ground near the back of the engine (rear main seal changed), it is probably the intake manifold or rocker cover. Anyway, I stored it for the winter with fossil oil and drove it for a little while with the fossil oil including some high boost "set-up" runs. No oil leaked.
Got the oil changed back to Mobil 1 synthetic 10W-30 and the oil leak came back with some lower boost runs.
Is this just coincidence??

 

[The Radius Kid]

Probably not.Synthetic is good at finding leaks were regular dino oil doesn't.
It usually just that the synthetic removes any varnish that accumulates around the seal fit and removes or dissolves it away.
Then you leak shows up. frown

 

[jdodman]

Synthetic oil will find its way out of almost any motor eventually. When I had my rear main seal changed, I went back to regular oil and have never had a leak from the rear again.