MOTOR experts are reassuring drivers who fear they may have irreparably damaged their car's engine by filling up with "four star" during the petrol crisis.

Many unleaded car owners are worried that by topping up with LRP -- the lead-free alternative to four star -- they could have ruined their engines and totally written off their catalytic convertors.

However, we contacted the AA and they reassured us that extensive testing had shown that LRP causes almost no damage to modern engines.

But some firms are still offering to "clean up your cat" with special machine and chemicals that will rejuvenate the pollution filter.

"Leaded petrol could ruin a catalytic convertor, but it has been illegal to sell leaded petrol since the beginning of the year, only LRP," explained AA's head of research and policy. "We tested a car with a catalytic convertor by running it just on LRP for 50,000 miles and we found it had virtually no effect on the engine and the efficiency of the catalytic convertor had fallen by just two per cent."

But Mr Philip Gavin, from MIS Consultants in Blackpool, is offering a service to remove contaminations from catalytic converters and says that it is too early to tell what damage has been done.

"I've even heard of one motorist filling up their unleaded car with diesel," said Mr Gavin.

"As far as I know, using LRP will contaminate your catalytic convertor.

"If the AA have found this not to be true, they don't appear to be telling their men about it as I spoke to one the other day and he said under no circumstance should you use LRP instead of unleaded.

"I recommend that people take their car to an MOT garage and have the emissions checked."