I have for a long time used TetraBoost (the latest mix is called EGuard15).
Its makers state: "TetraBOOST contains anti-acid formulations designed to minimise the problems associated with ethanol water absorbtion and acid formulation – unbeatable both for regular driving use and over-wintering situations"
Please note: It contains genuine TetraEthyl lead and increases octane levels. It is NOT suitable for a vehicle fitted with catalytic converters or permanently-mounted 02 sensors.
Mixed with super unleaded and with a motor running commensurately more timing advance there are appreciable increases in power and efficiency.
But, over winter, there's no substitute for (on a dry day) a really hard run for at least ten miles with enthusiastic use of brakes (to free up those pesky Morgan rear slave cylinders).
