my TW, 180k km, has suddenly started using coolant. The gauge is fine, it drives beautifully, no obvious leaks on the ground, no milkshake on the dipstick or visible thru the oil filler cap. I put a new radiator cap on about year ago, so that's probably OK. No damp spot on the passenger side floor. It's taken about 2 litres in the last 2 days, which seems a lot to me.
Any suggestions for the next step much appreciated.

