Fx4-Michael

So when I bought my truck in June it had a regular paper air filter in it. My jeep had a k&n drop in and it didn't give me a problem so I put a drop in on the f150. Well the first oil change i did on the truck under the oil fill cap was clean. When I changed the motor oil in October with the k&n air filter, it had this milky slimy moisture under the oil cap, however the oil itself was just dirty no milky evidence at all to indicate a head gasket problem. A few weeks ago I removed the k&n filter to clean it and reoil and haven't had a chance to do so. The k&n was used in my neighbors truck for a period of time before he got a cai and gave it to me. Anways I put the paper filter back in, replaced the foam gasket around the filter tray with new insulation foam and cleaned under the oil cap. Today I decided to retorque my spark plugs as I had a faint gas odor in the cab and checked under the oil cap and oil.. barely any milky moisture under the cap now (was a lot worse before the paper filter and new foam) could the k&n have somethin to do with the moisture under the cap, or was it the lack of the foam gasket before hand(it was toast and little pieces were in the k&n filter)? I'm stumped because I was just about to order a k&n cold air intake and sct programmer..

Any ideas? What's your opinion?

Kokeshx4

Could be from starting it up and shuting the engine down before it gets to its normal operating temperature, usually due to short drives.

Fx4-Michael

I only have a 10 minute drive to work but i let it warm up before I leave. However it has been in the teens temp wise maybe that has somethin to do with the lack of moisture under the cap as well on combination with the dry filter

Drooool

its got nothing to do with the air filter. short drives, cold temperatures, moist weather will all contribute to that milk oil on your cap. some cars like bmws are alot worse for that. i work on alot of nissans up here in Canada and when winter weather hits the caps are all like that.

powerranger262

The wifes grand prix gt always had this. Never knew it was from her 5 minute trip to work. I always take it for a beat run once in a while to blow out the carbon.

Fx4-Michael

Just a coincidence then that I take it off and it gets below freezing and the moisture under the cap lessens... Thanks for the help guys

bubbabud

The air filter has NO bearing on the amount of moisture [Condensate] in the crankcase this is caused by low temps and high humidity. the moisture tends to collect at the top of the engine [ oil cap] because its cooler than the engine block just like steam under the lid of a cooking pot. solution get the engine up to operating temp for longer periods just letting it idle in the driveway wont do this. If your situation doesnt allow this then change your oil more often.

Fx4-Michael

Thanks. I knew about the moisture in the crankcase causing the cap issue, just didn't know if the air filter may of had a connection also. I appreciate it. I change my oil and filter every 3 month because of my short drive. I also take it for a good highway run every other week to circulate everything longer too

JarreT329

I have the same milky crap on my cap. Its def not from the k&n filter