thall6594

2002 3.0L Quattro with 140k

Since I had the car it has burned a bit of oil, no big deal it's old. But I recently started having a 25 mile highway commute that I drive almost everyday and the consumption seems to have gotten quite a bit worse in the past month or so. Like a quart every 800 miles.

I had a full timing belt kit installed about 1k ago because my water pump failed, so all my seals, both valve cover gaskets, and belts were replaced with a new kit under warranty from Continental. There are no external leaks at all, and I've never seen any blue smoke coming from the exhaust.

I average 72mph and about 2800rpm while on the highway. The oil was changed about 2k ago and that was the first time I put T6 in because I read such great things about it in these engines. I was running full synthetic 5w-30 before the T6 with similar findings.

I read something about the crankcase breather hose being a possibility? Is it because I changed to T6?

Just Me

It almost certainly has nothing to do with the brand of oil. and going from 5w30 to 5w40 would typically make it marginally better.

Back up. How many times has it burned 1 qt/800 miles in a row?

Once? if yes, i have your answer. You've been using a little oil and replacing it with dilution (gas, water, acid) for ages, a drop or two at a time. Then you run it 30-60 minutes on the highway, and keep the oil > boiling. It all boils off at once and you see the drop.

Voila. Happens all the time.

Grant

thall6594

It wasn't at 1qt per 800, but I think it is getting worse actually, it was around 1qt per 2k miles for a while.

Just Me

If it continued for many miles then my theory is junk. qt/2k is not bad - well within limit. But it changed. I would not yet worry.

Grnt

thall6594

The qt/2k was almost all city driving, almost never revved above 2k rpm. I try not to wait for it, but I see the yellow "oil min" light every once in a while. Do you know how much needs to be added at the point of the light coming on?

I'll start recording how much exactly I am using.

Just Me

No clue but anyway, you should not wait that long. It essentially means you are waiting until you are running low on oil, potentially causing poor lubrication. Even on my cars that burn zero oil i check the oil every week or every fill up, when the car i on level surfaces. The gap between min and max is in the manual, but typically a bit over 1 qt. Doing what you are doing is making everything worse IMNSHO. That's what dipsticks are for!

Grant

thall6594

I check the oil pretty frequently, I have to check the coolant level everyday due to an unknown internal leak so I usually check both. Is there a better dipstick I can buy? This damn dipstick is so hard to read accurately.

I'm going to check the PCV valve when I get a chance, to make sure its not clogged or cracked or anything.

I like the idea of checking during filling up, gives me something to do while I pump those 18 gallons haha.

Prospeeder

I have seen this issue on a few 3.0 cars. The breather parts all need removed and inspected. There is the breather valve, the thing it attaches to, a hose from each valve cover, and a hose from the valley pan to the bottom of the thing the breather valve attaches to. The ones I worked on I found them clogged full of hard black gunk. These cars had about 120k on them.

My 2.8 A6 was using a quart a week. The breather parts were full of yellow oil/water snot. After cleaning them all out it uses no oil between 7500 mile oil changes on 5w40 synthetic castrol. It has 186k miles on it right now.

thall6594

Are you referring to that disc thing under the back plastic cover? Clean that and everything it runs to?

jcman

Check out this thread regarding the 3.0 crank vent system and oil issues for what its worth, somewhat related and very interesting indeed. https://www.audiworld.com/forums/a6-...witch-2859606/ and post #13