Genghis
I understood that you are an engineer, therefor you should know that the ead is for lubrication, important to the exhaust valve. All Lycomings and Continentals need it. Tests on car engines that have used 4*LRP showed very high level of wear. Fuel is cheaper than a new engine, but what about life?
Rightstuffer
Come to Elstree, we pay 82p+vat.