Some 26 million British drivers risk damage to their vehicles because they do not know what the oil light on their dashboard means, it has been revealed.Research carried out by car care company Comma, in the build-up to its National Oil Check Day on Friday 25th July, found three-quarters of motorists wrongly rely on the dashboard’s oil warning light to tell them when to top up their engine.In reality, the light only comes on when oil levels are so low serious mechanical damage is likely to occur, according to the group.Mike Bewsey, spokesman for the organisation, said: "Too many people think of their oil warning light in the same way as their petrol light when, actually, it's an awful lot more serious."He added by the time the light comes on, drivers could be a few miles away from "massive inconvenience and a repair bill just as big". Earlier this week, James Harrison, chief executive of price comparison website insurance.co.uk, recommended driving more slowly in order to cut down on motoring costs.