hi. im new to the forum and z's.... sorry
tried to find the answer to this question myself as to not be flamed...
ok, i added a powerlab plenum spacer yesterday, when i took off my upper plenum it looked like someone had crapped in it.... nasty brown film covering most of the inside.... 65,000 miles on car. is this normal?

 

probably just oil from the pcv system, look into installing an oil catch can.

 

+1 this is the result of no oil catch can SLUDGE

 

cool... thanks for the help

 

Just out of curiousity, do you have a rev-up?

 

https://my350z.com/forum/engine-drivetrain-and-forced-induction-diy/237059-homemade-catch-can.html

that should take care of it.

 

edit: dumb question lol.

 

your crankcase gets air from your intake. a result of the intake suction is that it pulls a small amount of oil into the motor. a catch can goes in this line and will be a holding tank for any oil that passes throgh allow the air to still flow. so technically no more oil will go into your motor so in a way yes your car would burn less, even though the same amount of oil that would have been burned would now be in your catch can.