I got a decent amount of oil that settles onto my inlet every time i boost real hard, i'm running no filter its on a top mount so its very noticable. I have'nt pulled IC pipes or the DP checking for oil. Its not really any symptoms other then the oil in the inlet.

what could be the cause?

 

sounds like blown seals to me...

do you get any excessive smoking out the back after you let off the gas??

any oil in the tailpipe?

Probably a blown seal on the inlet side, and possibly on the exhaust side too if what your saying is so.

check your chrge piping for pooling, and an oil/dust "swirl" running thru the piping.

 

my gt30r does the same thing but it doesent smake and no oil gets inthe charge pipes.. it could be just oil pressure get a bit too high @ wot run a smaller oil restrictor