Here's a conundrum for you all.

Had the engine rebuilt a couple of months ago and ever since, the car has been using a fair bit more oil than usual. Infact about a litre every 800-1000 miles.

The car is approaching 140k now but no leaks, the car has been back to the engine rebuilders, who are scratching their heads as can't work out why. No leaks anywhere, no tell tale turbo going signs like oil misting on rear bumper (5p size spots).

Just seems to use more oil. I'm now using 15w 40 as it seems better and slightly better for older engines. Undersidfe of car is clean. Intercooler has been off and all pipes checked, which are totally dry.

Tail pipe is slightly darker but nothing extreme, bit blacker rather than grey. I and the engine rebuilders are puzzled. It's not extreme (Des tells me it is good, as constant new oil is good for the engine - a positive spin no less).

Any ideas peeps? Just curious.:confused:

I take it you dont see any oily plumes when gunning it ?

Best time would be in the dark with another car behind you so you can see the smoke in the head lights...

I'm sure its not normal for the engine to use that much oil in that space of time but if there are no leaks and no real sign of it burning oil there isnt a lot you can do.

What was the useage like before?

Well, I've heard of newish VAG engines using oil at this sort of rate before. OTOH there are others like mine where the oil consumption from a weekly dip test would be higher than that from all other causes!

Mine used a bit under a liter of oil when it was pre-10k service. It stabilised and stopped loosing oil.

No smoke of any description. Didn't really use much oil before engine rebuild. Must be related but no idea in what respect. The engine is high mileage now at 140k but no leaks. Hmmmmm

What did the rebuild involve?

If it's consuming oil it must be either leaking out, or consumed by the engine. There are no other possibilities.

Depending on the amount of oil, there may not be enough smoke to see.

You've said your tailpipe is a little blacker, so that lends weight to the theory that the oil is being burnt or ejected by the engine. Since you're not seeing it on the input side, it's probably either coming down the valve guides, or up past the rings - which leads back to the original question ...

Hold your hand or a piece of white paper in the exhaust with the engine running and see if you get any oily blackness thereon.

What did the rebuild involve?

that is what i was going to ask ,

if it had pistons/rings these may not have bed in properly and glazed the bores

the valves or guides may be worn , stem seals gone hard or worn

or a crackcase breather oil separater is allowing too much oil into the intake system

1cc of oil every mile is not a lot when you think about it , which is why its sometimes not possible to see any smoke in the mirror , try following someone driving your car and get them to boot it , this may give you a better idea of any smoke

New engines often burn more oil than those that have been run in. If your engine has been properly rebuilt you can consider it as a new engine and I would expect the oil consumption to fall over the nexct 2 or 3 thousand miles as things start to bed in.

The Owner's Manual says that consumption can be as much as 1 litre/1000 km. Yours is less than that. I wouldn't worry at this stage. I would however check the dipstick regularly and monitor the actual oil consumption carefully. When my son had his Audi S3s 1.8T engine rebuilt recently, he ran it in carefully over an extended period.