Where's the oil going?

I've been having to top up the oil over the last few months in my 02 160. OK it's done 120k, but not burning that much.
However, it came to a head last week.After standing for about 10 days, with the oil level just under the full mark, gave it a run & after about 8 miles the oil warning light came on
Pulled over & checked dipstick - Zilch :nonod:. Topped up with a ltr. of oil & returned home. Decided to get it checked over at local MG garage next day, 3 miles away & the warning light came on again on way there.
There is no evidence of any oil leaks under car or in the engine bay & the mechanic is as baffled as me.
No oil in water or smoke from exhaust, so where is it going?

Despite the lack of blue smoke in the exhaust and given that you don't have any leaks I think it must be being burnt. Did the mechanic run a compression check or a cylinder pressure check? There may be a 'bad' piston or possibly a valve guide issue.

Richard

As per Blown-in’s post above:

If there are no visible external leaks and no emulsification to the coolant, then the oil must be being burnt in the combustion process, either by worn oil control piston rings or inlet valve stem seals, or if the compression rings are worn then by crankcase pressure sending oil vapour into the inlet manifold via the breather pipes.

A good start point would be a compression test and cylinder efficiency test.

Brian.

That's a conundrum!

Using that amount of oil would normally give obvious signs. Either plumes of smoke or oily residue over the bottom of the engine and rear of car.

Basically, as explained above, there are only three places the oil can go. External leak, combustion, or into the coolant.

One site of external leak is the bottom of the dipstick tube. This doesn't really oil up the engine.:shrug:

An emissions test should show strange results if you are burning oil.

Finally got car back from garage.
They have fitted a new oil pressure switch & also replaced rocker cover gasket, which had a small leak.
I gave it a 30 mile run & all was well - no light on & dipstick showing full.
I am still puzzled as I'm sure I lost a fair amount of oil previously. Could the OP switch have worked loose causing this?
The mechanic didn't mention this, though.
Will be checking oil level now after every journey :yesnod:

I've seen oil pressure switches fail, with a great loss of oil, due to the guts being blown out of them

i build mercedes 906la diesel engines...... the oil switches on them are in most cases leaking oil and have to be replaced....the plastic centre loose inside the outer metal body.