Some of you will know from my previous post that my local VX dealer found a large amount of oil in my coolant (expansion tank).

I was totally unaware of this and quite surprised by his findings. I usually check the coolant level once a week.......and had spotted nothing amiss.

Oil cooler failure says the mechanic.....that will be £487 please, Sir. . I declined.

Marks DTM has kindly offered to rectify the problem for me as soon as he retuns from his jollies.

Following his sage advice and using Mr Tunnie's maintenance guide I have repeatedly drained the cooling system. After some half dozen flushes I ended up with pure clear water. I also removed the expansion tank and thoroughly cleaned it. It is now as clean and sweet-smelling as a virgin's honey-pot. I then refilled with water ( Zero anti-freeze in the coolant at present)

I have used the car for a number of short journey's since. Necessary journeys of a few miles only, adding up to about 100 miles in total. Upon lifting the bonnet I expected to find the expansion tank and radiator thick with engine oil again.........BUT NO......

There is a slight  greasy discolouration on the inside of the tank.......but by and large the water in the tank is still clear. Hmmm. How is this possible?.

Mrs Opti informs me the answer is glaringly obvious, but apparently I'm too thick to fathom it out. When the car was at VX.........( insert your answer here)....I hope this is not the case. 

The question is: How long did it take to get that oily?

It might have built up over months, in which case 100 miles may not have been enough to make a noticeable difference. Then again, you say you check it regularly...

Opti wrote on 26. Aug 2011 at 12:20:


You have a way with words, Opti!!

Here are two photographs. Before and after.

9 Miles after Vx cambelt change



Roughly 100 miles after draining the system. I did not use a professional degreaser, so there could still be a few traces of oil in there.

I think this needs investigating properly.  I don't suppose you have any of the original sludge and a friend who works as a chemist by any chance.  It would be great to see if they had done.something unethical and then prove it......

I'd take it back around the garage and say look, no oil after 100 miles, how could that have happened?

Show them before and after photos & ask them what the hell the did when it was in your care. Bluff a bit and say you will involve trading standards 

Oil in header tank does not look emulsified or churned up by the water pump and being sent round the system. It's just laying on top, and no oil initially when draining the rad would tend to back up the sabotage theory... 

I would keep an eye on it for a week or so, if still ok then add antifreeze and keep running it.

It could have been an old failure which has not been well flushed.