Toni Clark, European RC distributor for many years tested several oils and, the oil they recommend for the Valach Motors four-stroke engines is Valvoline SynPower 2T.
The extremely good BelRay H1R, we use for our two stroke engines, is not ideal for petroil lubrication in four-stroke engines. BelRay H1R burns off very well and deposit free, but it does not blow down past the piston rings into the crankcase as well as Valvoline SynPower 2T.