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Do I need an E5 additive for my classic Daimler?
I am fortunate to have and look after a 1969 Daimler Sovereign (420). I am having to use E5 fuel and would appreciate your guidance on which additive(s) would help protect the Jaguar XK engine? I believe lead replacement is less of an issue with this engine but I am concerned about the adverse effects of the ethanol content of E5 petrol.
Asked on 4 August 2023 by Patrick Begley
Answered by
Alan Ross
All XK engines can run happily on unleaded fuel (with no additives) because their alloy heads had to be fitted with hardened valve seats. However Jaguar specified 5 star petrol because of the 9:1 compression ratio so I suggest you use Super Unleaded wherever possible - Shell V-Power, BP Ultimate or Total Excellium. It's a small price premium but given you are unlikely to be using the car as a daily driver it will be money well spent with no pinking and a more spirited performance
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