i read something a while back and it was this test that was done on fuels. i cant remember the exact figures but good fuel has about 15 additives and supermarket fuel was tested to have 7 or less. it was along those lines so dont quote me.

i know of 2 people close to me so not chinese whispers who had breakdowns due to supermarket fuel. one friend had a £1500 payout as ther was a big case of bad supermarket fuel a few yrs back. the other had the tank drained by the AA as car broke down. a refil of good fuel and all was fine.

i use supermarket fuel almost never. iv aslso spoke to a few people with diesel injector problems and when you ask them where they fill up its almost always supermarkets.