Taking out my generator with the engine in, ended up taking out the whole shroud. And found a bl**dy great mess... the vast majority of which is on the left of the engine. The dog house oil cooler looks to have either lost its seals or developed a leak and I don't know how to determine which. I have no idea how long that oil cooler has been in there, but there's generations of gunk on the inside of the shroud which is proving a joy to remove. Before I go spending $$ on a new cooler, is there any way of telling if it's still ok, or should I just chuck it and be done with it?
Cheers, Angela.

Have a oil cooler test tool if required. Clean your engine block around #3 cyd as block may have a crack. 0422983260 cheers

Thanks for the offer, much appreciated. I rang our local VW shop to find out parts prices and he's offered to test the cooler for me, so I'll do that since he's quite close by. I'll give the block a good scrub and hope to god no cracks are hiding under the gunk. Still, this does explain the occasional oil light flicker, unfortunately

The oil light flicker simply means that the oil pressure is momentarly going lower the the pressure switch rating, could mean a bit of internal wear or the switch could be a problem.