IDUA ORTTAUQ 6A

I recently bought this 97 A6 Quattro Avant, it had 93K and seems to run perfectly. I have changed oil to Mobil One 10-30, and now have 96,000 miles. In this time I have had to add 4 quarts of oil to top off, all within 3,000 + miles. There are no leaks, no apparent blue smoke out the exhaust!

On another Audi forum I posted a question as to why? The response was that I needed to switch out the PCV valve and do a complete SeaFoam treatment.

There is no PCV valve as leter posted, and I could not find such for replacement offered for this model car. Back to square one..........why is this car, engine, consuming extreme amounts of oil?

Others report normal usage, 1/4 quart between oil changes, or none at all. Something is very wrong here and before I drive, before I start the engine again, I need to know what, where, how, and why?

Is there anyone here who may shed thoughts, or know why?

I'll repay you with positive brain transmissions wishing all great things happen for you.

islingtonaudi

Is it leaking somewhere? That sounds excessive even for synthetic.

rmccomiskie

1/4 quart between changes is optimistic. More like 1 or 2 qts in 6,000 miles for me.

Biscuit141

I have put in maybe 1/2 a quart or so, but not very often.

islingtonaudi

I need to figure it out and perhaps I'll burn a bit less. Aren't factory specs up to 1 qt. every 1k?

IDUA ORTTAUQ 6A

I've heard the same thing, 1 qt to 1000 miles, but why so many use little to none between changes?

rmccomiskie

They decided to design the 12V with loose tolerances to reduce internal friction and increase fuel economy. They considered the increased oil consumption of a loose engine a good trade off.

The 1.8T engine, on the other hand, is designed with tight tolerances and uses very little oil. So, blame the engineers every time you add a quart to your 12V.

Actually, refreshing the oil by adding some between changes does wonders for the longevity of the oil. Five quarts in an engine that doesn't lose any oil will have an average of 1,000 miles on each quart at a 5,000 mile change (5,000 miles divided by 5 quarts = 1,000 miles average).

Let's suppose the same engine loses 2 quarts during the 5,000 miles with 1 quart replaced at 2,000 miles and 1 quart at 4,000 miles. The total oil exposed to the mileage is 7 quarts (5 at the change plus 2 added). So, the average is now 714 miles per quart (5,000/7=714.2). This is the refreshing effect of adding oil between changes. You could extend your oil change interval to 6,000 miles and the average would be only 857 miles per quart. Still less than the 1,000 mile average seen with no oil consumption. Add another quart at 6,000 miles and go for an 8,000 mile change. Average would finally be 1,000 miles per quart (8,000/8=1,000).

I log everything that goes into my car so I can calculate my average miles per quart and determine when to change. I feel 6-7,000 is safe with synthetic oil that meets VW 502.00/505.00 specs. Doing this offsets the higher oil consumption with less frequent oil changes. Nerdy eh?