Apparently there is no PCV valve, 97 A6 12Valve 2.8,to clog, which if there was one might explain thehigh oil consumption! After reading a post on another Audi forum about a similar situation, drivingmy 97 Audi A6 Quattrocar any further is detrimental, according to that post! In my effort to preserve this car for future use, I have grounded it (so to speak) until I canunderstand why it is using a quart of oil every 600 to 800 miles, I know I said a thousand miles earlier, but actually it is worse and probably why the last owner parted with it. Now I'm faced with a $5000OIL BURNER that ultimately will take out the catalytic converter (short term) and who knows later what's next, assuming oil is notacting normal in this engine.Anyone have a clue?

 

I would try running a 3/4 can of seafoam in your crankcase for about 50 miles or let it idle for an hour then change the oil and filter. If that doesn't fix the problem i have no idea where that oil is going, it may have a major leak thats really hard to find or a blown head gasket. My bet would be a leak.
After doing the seafoam, put in some oil dye that you can use a black light with so its really easy to find a leak.

 

I know this might seem kinda dumb, but as much oil as I am using, it should be VERY appearent, it should be dripping off the rear axle-differential, actually coating the entire underbody of the car! All is dry as a bone! So it must be going out the exhaust.

I have posted this question on the other Audi forums and I am beginning to hear same case senerios, and they are asking me for answers! I shall try the Seafoam treatment, but liked your PCV solution better. So how did Audi by-pass the PCV application for the 12 valve 2.8? And where does the actual ventilation take place with this engine?

I am not going to drive this carone inch furtheruntil I find out why! ..........The best car I have ever owned, for all the good reasons, a 1990 Volvo 240 wagon......... I once owned a 1965 Corvair convertable, only had 45k, paid $50 for it, paid $60 to dispose a month later![]

 

I really couldn't tell you why audi didn't use a PCV valve on a 12V engine, you would have to ask a german engineer, they don't tell us un-less we need to know. [:@]I doubt you would get a good answer from them either, i would say the person with the most experience on the old 12V engines is Dave or (techbod) so you might wanna ask him that question. Definately try out the seafoam though, unless Dave has some better insight.

 

Well thank you for trying on this one. I realize I have an older Audi, and it isno longer onthe radar screen for issues, now 10 years after it left the factory. Most of the members here own newer than my Audi car, most with much much less mileage and dealing more with performanceupgrade interests.

If I find the reason for my issue, I'll post ithere...Steve

 

Another thought: check the coolant. If you blew a head gasket, it could be bleeding oil from one of the internal oil passages into the coolant jacket. Granted, with the amount of oil your car is eating I think you'd damn near overflow the coolant tank, but hey, ya never know.

(Side note: best car I ever owned: 1988 Volvo 240DL Sedan. Man, was that thing easy to wrench on! Except the @(#*$( oil filter. Who the hell thought it was a good idea to put it right below the exhaust header?)

 

Audi claims a consuption rate of 1 quart per 1200 miles to be normal. Most manufacturers consider a quart per 1000 miles normal. Your consumption rate is close to normal. Im willing to bet that the rest of your oil consumption is due to multiple small leaks. On that engine the vally pan gasket leaks(under the intake), the valve covers leak, the headgaskets leak, and the oil pan and filter can also have small leaks. None of which needs to be major, but if a little leaks out at each point it can add up without a mess on the garage floor.
In any event i wouldnt be too woried about the cats. How many gallons of gas do your burn for every quart of oil you burn in 600-800 miles?