I have the following engines and would prefer to have one jug of fuel for them all.

2 Strokes
OS 46 FX, GMS 47, Irvine 53, Sport Jett 50

4 Strokes
YS 63 FZ, Saito 100

I was using 10% nitro fuel and ran out so I bought 2/4 cycle with 15% nitro. The only engines currently in planes are the GMS and the Irvine. The GMS took a little adjustment, as did the Irvine (both ran great on 10% but I was told the 4 strokes would need more than 10%). But when I was doing final adjustments on the Irvine, it stopped and would not start. Worked on it at the field and gave up. Got it home and removed the cowl on the plane to find I had blown the head gasket. Could this have been caused by flooding the engine or the 15% fuel? The manual says the Irvine can take up to 20%, but many posters here say no more than 10% without a head shim. I would prefer one jug of fuel for them all but understand if I cannot get away with that. Will all be fine with 10, 15, more, less? Any help is greatly appreciated.