Coolant and other stuff

[cocker]

T25 1985 Caravelle 1.9DG
To cut a long story short, I recently overheated and lost some coolant, upon investigation I found a slight leak from the offside water jacket. Thought I'd try some Wynns and opened the expansion tank to find what looked like liquid rust. I drew 500ml off and put in the Wynns (which didn't work), when it had settled about 10mm of sediment had dropped out. This raises some questions:
1. Which is the best coolant to use? I have been using red OAT.
2. Is a leak from the water jacket ( and the presence of liquid rust) indicative of further major problems ahead?
3. Does anyone know of a reliable VW garage capable of fitting a recon engine in Worcestershire should it be necessary?
4. Can you successfully flush out the WBX plumbing?
Any advice would be appreciated. I have read the wiki and the forums and other vw sites and am still confused.

[kevtherev]

Your coolant should be clear and pink
(G12++ or equivilant )
Rust suggests the wrong or too weak a antifreeze has been used.
The antifreeze is first and foremost a rust inhibitor.

The cooling system can be completely flushed using a hose.

[Oldiebut goodie]

Some of those leak stoppers give the appearance of rust in the water - if it is a new to you vehicle it may be a previous owner's attempt at sealing the leak.