I've had my Passat since I bought it from a dealer ex-lease in 2002. It was high mileage (105,000) but in good condition and with a complete detailed service history from the leasing company.

It has served me well for almost 5 years and has now reached 181,000 but it's always had an intriguing coolant problem!

I'm after advice on flushing the cooling system since it's had some brown contaminant since I owned it. The plastic fill bottle was opaque so I had it replaced, but it still seems to have the brown stuff slowly shifted round the cooling system and into the bottle, leaving a fine layer I can wipe with my finger!

Can someone suggest what I should try for flushing this out please? [I can't seem to find any official VW solution and I've heard about washing up liquid or soap powder as possible answers]!

PS I suspect it was caused by the previous driver who tried something off his own back, since there's no mention of any cooling parts or problems on the leasing company's extensive service and repair list!

Thanks - Julian