Before anyone can say anything exactly, we got to know what engine it is!?

Anyway, my brother's '85 Transporter with the 1,6l TD had a massive oilleak from around the oilfilter. The problem was that the large o-ring (it's called something else - but I don't remember what!) between the aluminum "angle" mounted on the block (With one of the oilpreassure-senders) and the oilcooler (mounted on the TDs) had hardened and had cracked in about 5 places! When the engine idled for about 10 seconds - there was already a large pit about 7-8 inches in diameter under the car! And he actually drove the car like this! Adding as much oil as diesel....

The new o-ring costed about $4 (US) at the dealer and fully cured that problem.

I hope this has been of any help, but it's hard to know what you're talking about without knowing what engine it is!

Christian