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Matthew Wright

My Air Filter Is Turning Into An Oil Filter

By August 7, 2008

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Multi-tasking is great. Anybody with the ability to do a few things at the same time (like pretty much every mother on the planet) and do them well has been truly blessed. What's true with parenting and circus clowns doesn't hold when it comes to your car's systems. This reader's air filter has turned to multi-tasking, only it's not a welcome change.
Dear Matthew, Thanks for providing so much useful information on the site. I have been able to try and successfully pull off automotive feats I thought were out of my league by a long shot! Recently while doing my regular maintenance I went to change my air filter and found that it had what appears to be motor oil splashed on it. The car is a 1991 VW Jetta, manual transmission with 148,000 miles. I know it couldn't possibly be oil from my engine. Is it possible that some black fluid was splashed into my engine from the road? I can't figure out what to do, or if I need to do anything at all. Please help, Travis
Travis, congrats on almost reaching the 150k mark with your Jetta. You must take pretty good care of it. As for the oil on your air filter, no it probably didn't splash up from the road and it is oil from your engine. How did it make it all the way to your air filter? The PCV valve. If your PCV valve goes bad, the entire system can back up, spit up and screw up. So far yours has backed and spit but you caught it quick enough to avoid the screw. Replace your PCV valve and your air filter will be pristine once again.
August 8, 2008 at 12:41 pm
(1) mikey says:

150000? 91 silverado 5.7 5 speed, 391000 when I sold it, 89 mazda mx6 5 speed 346000 original clutch when we have it to my mother in law! 86 gmc jimmy, 457000, still driving, but is on 2nd motor, 75000 on it this time around. SERVICE SERVICE SERVICE. I could have bought a new car on the oil changes alone!
yes I completed ALL maintenance. except balanceing the tires.

August 10, 2008 at 9:57 am
(2) teamxlrr8 says:

Mickey…good job with your high-mileage vehicles,but there is 1 factor that service cant help…RUST,RUST,and more RUST! keeping the undercarraige clean maybe helps but in my region(S.E. USA) rust is a growing problem which is cutting the lifespan of many cars & trucks.

August 11, 2008 at 9:02 am
(3) Greg K says:

Travis, I hate to see such firm, “this is the cause” answers given to your type of question. Will a new PCV valve fix the problem?, maybe. Be sure to check for vacuum flow thru the PCV valve first. If there is a good vacuum draw, then it’s probably not the valve causing the problem, but more likely internal engine wear cauasing excessive blow by, that is too much for the PCV to handle, allowing oil carrying fume to reach & saturate the air filter. IN your case I hope it is only the valve, but you needed to know that the real problem may lie deeper.

August 11, 2008 at 3:18 pm
(4) autorepair says:

I guess you’ve never had to service a ’91 Jetta. It is without a doubt the worst car Volkswagen ever produced. They slashed the budget in 1990 and didn’t quite have it together for ’91, so the worst Jetta ever was born, and promptly started dying. I’ve never seen so many starting problems, transmission issues, emissions nightmares.

August 12, 2008 at 11:34 am
(5) Charles says:

Don’t watch the tech/mechanic!!!Keep your eye on the man with the pencil!!!!!The words HONEST and AUTO REPAIR should not be used in same sentence!!!!!!

November 5, 2008 at 8:16 pm
(6) Carl Peterson says:

I have an 86 VW Golf with about 282,000 Miles on the engine and I recently failed in regards to oil. Not only did I over fill the engine, but I had the wrong grade, which wasn’t my fault. The engine expelled about a quart of oil through the PCV tube, because there is no valve on my car, and into the airbox, which then pooled and then sucked the oil into the manifold…long story short it sucks. I’m wondering now, how do I clean the air filter, or do I have to wait it out after I clean the intake manifold and box?

May 5, 2011 at 9:13 am
(7) Earl says:

I’ve got a 2010 Ford Focus which has had a harshnes in the gas pedal since we took it off the lot new on Jun 4 2010.
I changed the OEM air filter at about 1,500 kms. replacing it with a K&N filter.
I took that filter out at 13500 kms and its oil soaked black. In jsut over 6, 000 miles its heavily contaminated for some reason.
Ford has been dealing with the car problems for almost a year.

I’m tired of this piece of (another 4 letter word – not Ford)

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