97 1800 Engine Flush - StuartD77
Now established that my oil pressure problem is due to a build up of carbon which is clogging up the oil pick-up.

Is there an engine flush on the market that will loosen AND BREAK DOWN any traces of carbon in the engine?

97 1800 Engine Flush - 659FBE
No. It will have to be taken apart and fully cleaned, probably with the fitment of a new oil pump. I hope it's not too late - it sounds as though the bearings have had a hard time.

This engine seems to need fully synthetic oil and probably more frequent changes than is specified by VAG.

97 1800 Engine Flush - yorkiebar
There is such a thing as flushing oil, designed to er flush.

But I would not recommend it, I would only use it on an engine that I was about to strip, just to get it cleaner for working on.
97 1800 Engine Flush - 659FBE
Flushing oil with a blocked strainer = more blocked strainer. It shifts the carbon and other gunk rather than putting it into solution. I know of no substance which will do this, which would be safe to put into an engine.