Well the oil change time is almost upon me, was lookign about at a different oil this time to my regular Millers XFS 5w40. Castrol edge was £17.95 p/l in local shops but i spotted Mitsi in Derry selling it for £10.95p/l. Is it good stuff & should i change from 5w40? Currently got a full exhaust system with decat, running 1bar with grade 7 plugs, k&n panel filter