Some of you might have read other of my posts where i ramble about what oils i could try for my next oil change well i've stumbled upon Motul 7100 4T 20w50 which is a synthetic ester based motorcycle oil , do you think this would be harmful to the seals on a 40 year old car like mine? Despite being a 20w50 will it just start [censored] out the rear and front main seals like i've read on other forums?