Run the car exclusively on Shell V-Power and you will never have any fuel system problems as a result of hydrocarbon deposits. You will also benefit from better performance at both high and low revs, and better economy if you use the better performance at low revs. I have been doing this using V-Power and Optimax petrol for 10 years and despair at the number of readers who use the cheapest petrol, then have problems as a direct result that cost them far more than any saving they made from buying the cheap fuel. Shell V-Power diesel and BP Ultimate diesel have cetane improvers, detergents and lubricity enhancers that ensure fuel systems are long lived.