as someone has said its basically a parafin, which if u do a simple test yourself,

i.e wipe some oil on a piece of glass with ur hand use this so called cleaner on the oil and it should be gone and the surface oil free, that will show u if it works or not.

Me what i usally do is brag 2 x wynns (http://cgi.ebay.co.uk/ws/eBayISAPI.d...m=290136699222 ) bang them both in, take the car for spin approx for 20 mins, come back oils nice n warm, and then drain the sump. i do mine every time the oil start getting dirty, approx 8k miles, and thats on a 98k zetec lump!

if i dont use that then i usally bang a cup of petrol in the oil and give the motor 10 mins running at idle then flush it all.

been using wynns and the petrol method since the day i got my motor, and its still going, not one fault no extra knocking etc. run's fine drives great.

On a side note i also stick approx 1 litre of diesel oil in along with my usal castrol gtx 5w,30 oil to, xtra cleaning and seems to be quieter on startup especially in the cold.