Oil usage

[Nick Jones]

1996 4.2QS ABZ

Uses lots of oil. Like a litre every 500 miles or so, possibly a bit more. It may leak a bit (there is a leak from somewhere around the oil filter housing) but not that much. There is no oil in the water.

I have seen the odd puff of smoke on start-up (more often when warm) but not that often. No visible smoke when driving. Exhaust does not smell like it's burning oil when cold and the cats are still working so no smell at all once warm. Seems to go ok. I've not yet inspected the plugs to see if they show signs of oil burning. I've not compression tested it either, but aim to do both soon.

Oil was changed just before I got the car (about 2,500 miles ago), PO said he used 5 -30 synthetic. I've been topping up with 10-40.

Indicated mileage is 139k. However, though there is quite a bit of history, there is not enough to verify this. My guess from the general condition of the car is that it's done more, possibly alot more (my 284k '96 C4 A6 seems less knackered in all respects!).

I did replace the (completely disintegrated) breather pipes when I first got the car.

Are there any known failure points - valve stem seals, bore coatings etc that are known to cause excessive oil use?

Thanks

Nick

[mannyo]

The leak down by the oil filter is going to be the oil cooler, a very common failure as you may find by reading the forum. The usual failure is a plastic pipe between the cooler and the engine, but that usually results in loss of coolant. Oil down there would suggest one of the seals has failed between the cooler and block, its major surgery to repair based on the invoice I had with the old D2.

[Nick Jones]

Thanks.

I'm aware that the oil cooler can be an issue. At this point I have no coolant loss and no oil/water mixing. Also not a massive oil leak so I'm pretty confident this is not the prime cause the of the oil "going missing". I'm not about to get involved in that world of pain without good reason, especially with a wide range of other faults to deal with.

What is the normal range of oil consumption for the ABZ engine?
Are there any breather issues or tweaks that can help?
Are there known bore/ring issues as with some of the other Nikasil technology engines of this era?

It does go ok but the irritations are beginning to outweigh the pleasures.

Nick

[Goran]

Audi coating is Alusil and as far as I know has not had any problems like Nikasil did.
Check also the joint between transmission and engine. There is a big round seal at the back of the engine hidden by the transmission, this almost always seems to leak as it rarely gets an opportunity to be changed.
Oil can possibly collect in the bell of the transmission? and not be easily seen?

[Nick Jones]

So I've pulled the plugs and done a compression test today.

Compression test was done warm with all plugs out and throttle closed (my initial test showed no difference between open and closed).
All were 15 Bar +/- 0.5 Bar.

All of the plugs on the right hand bank were loose, especially #4 (rear) which also had quite a bit of oil around it. Couple of the others on that side had a bit of oil on them. Clearly the cam cover gasket is past its best.....

Plugs laid out by car position. #1 is top right. Car had partially warmed up from cold, mainly at idle, so colour may not be fully representative.


Couple of slightly crusty ones on the RH bank. #2 and #4


Close up of #2


Close up of #4


Was expecting worse to be honest......

What's it doing with the oil?! Doesn't seem like there is enough on the underside of the car or on my drive to account for the amount going missing.

Nick

[MikkiJayne]

Have you had someone drive behind you to look for smoke? It can be very hard to see while you're driving.

I've seen a 3.7 32V burn a lot of oil because of dried-out valve stem seals, but that did make visible blue smoke.