Marks DTM Calib wrote on 27. Aug 2011 at 18:10:



Thanks Mark, I'll keep in touch. I'm not convinced either way at the moment. The expansion tank  seems to be picking up quite a lot of greasy/oily sludge.....although the water itself seems reasonably clear.

If I had to take a guess, then I'd say the OC is the problem......but...

It may be worth my while to flush the whole system again......very thoroughly.

Do I need to buy professional degreaser? I heard that a cup ( or two) of washing powder run through the cooling system before being properly flushed out does the job.

I don't want to add 4.5 litres of anti-freeze .......only to find a week or two from now it's contaminated with oil.  

A small amount (i.e. less than half a cup) can help to degrease the system very well.

I've often considered a couple of dish washer tablets as an engine de-greaser as they are aluminium safe I haven't actually tried them maybe someone who has can post results.