KKB

I have a 2000 TT with the 1.8T engine. Been working resolve a similar issue where the oil pressure drops after it warms up, this appears to be intermittent but it has been tested by a audi repair shop and they are seeing it happen.

Oil pump was changed, $900 bucks. They checked the engine for sludge and found none but they flushed it anyway.

Crank and main bearing are also in perfect condition, according to the mechanic. Because they don't know for sure what the issue is they recommended replacing the oil pressure valve in the oil filter assembly. This is another 600..

Don't know what to do with this car, the car is in great shape, except I have this oil pressure issue.

Should I try SEAFOAM?

CRAZY_RUSSIAN

your not going to hurt anything with seafoam, but i dont think it will resolve your problem...
and on 1.8t, i really cant give you any advice as im not too familiar with their internal components.