I wrote about this in another thread, but for the benefit of future searchers, thought it would be better in its own thread....
After changing the oil in my van at the weekend, I took it for a short run out. As I pulled back into the drive 15 minutes later, the coolant light started flashing (first time it's ever done this, apart from the test flashing after start-up). Stopped engine, popped the lid and checked both the coolant tank and the expansion tank - both at the right levels. Once cool I took the dalek cap off and found the underside covered in butterscotch Angel Delight (well, sadly not that). Cleaned that off and as soon as I did water from in the cap poured out the spout... looks like the gunk had blocked the Dalek cap. Cleaned up the cap, reinstalled and bled some air out the rad for good measure and the van now running ok with no further flashing red lights. Couldn't see any more gunk in the tank.
Browsing the forum I found a few threads re residue in the coolant that led me to fear that (as an old, Italian mechanic once described a scooter of mine) 'the engine, it is like an old man who approaches his retirement'!
I've bought a new VW dalek cap from Brickwerks, so will fit that when it arrives.
I'm confused though as I thought the flashing light was a coolant level warning, not coolant temp - but levels were fine?
So, I'm thinking it is either:
* oil in the coolant from somewhere - bad bad bad

or
* the new Comma Red antifreeze reacting with what was in there before due to not flushing it out fully (I thought I had done). The stuff that was in there before was unknown age and to be honest seemed little more than water to me.
Interested in peoples' thoughts on this - time to start searching for a replacement engine or just wait and keep a close eye?

Thanks as ever for your time.
Stu