I tried switching to amsoil 15w40 twice and everytime i do the front crank seal leaks but will not with valvoline prem blue 15w40. Truck has 142,000 miles on it, change front seal at 95,000 and as long as i don't use synthetic have no leaks. Also used cummins seal when I replaced it. Also I have more blowby when I use synthetic. Anyone have any clues to why this is happening? thanks

 

Anybody got any kind of feed back

 

hi
i use the rotella 5 w 40 synthetic and do not have any leaks sence i swicthed last year ?

also use it all year and did not see any oil psi change compared to regular oil .