at 83000 miles and my tech told me that i might have oil sludge and to take it to the dealer because it should still be under warranty...2001 a4 1.8t quattro. i dont know if i can come up with all my oil change receipts and whatnot but i change it every 5000 miles.

I have never heard of a A4 with oil pressure problem that has had oil changed at 5k intervals, It is not a Classic thing about reciepts, its an Audi, all dealers have the same requirements,

I remember I had a problem while under warranty and took it in to Classic but didn't really ask questions. Is it simply because Audi gave change intervals that were too long?

Every car I've owned had a maintenance log in the owner's manual. Basic info like date/mileage was all that was recorded.

Audi maybe different, but it's worth a try.