Norwich-based Holden Group, which includes Renault, Honda, Volvo, Saab, Mitsubishi and Chrysler Jeep dealerships, is taking part in Esso's top-up and upgrading to synthetic oils training programme.
Chris Carey, Holden Group chief executive, said: "We trained 50 staff in February and are already seeing the benefits. Because the training was so accessible, our staff were really keen as they knew that in the long run it would make their jobs easier."
HR Owen's Colindale dealership in north London took part in the training programme last year. Craig Gallacher, dealer principal, said: "The training made us look closely at how we worked as a team and how we could do better."
To keep track of how the training improved service levels, mystery shoppers visited the dealership and also contacted it by phone over a three-month period. Service levels were assessed.
Mr Gallacher said: "We have just had our annual figures through and the result has been a definite increase in aftersales profits with oil taking the lead."