Filthy on petrol

THE week before Christmas my Mazda 3 was almost immobilised by a filthy batch of BP premium petrol. It cost me $540 to fix and BP denied liability. I did not have a receipt, though I had patronised the servo for 15 years. Then, in January, I decided to try Shell V-Power at another servo and -- would you believe it? -- my car was again affected, though not as badly as the first time. This time it cost me $275, I had a receipt and the servo operator admitted she'd received other complaints. A Shell representative rang me promptly and has agreed to cover all costs. Shell's attitude was in marked contrast to BP's. They seemed extremely anxious to help. Is this issue a common problem? Also, an RACV adviser said that adding a litre of methylated spirits to the tank breaks up any water. Do you agree with this remedy?