BelRay 40:1, 100% synthetic oils, raced desert on MC1+ back in the 80ies at 50:1, jet right no problems. Oil lubricates, fuel keeps engines cool, oil burns at a higher temp. More fuel, right jetting with good lubricant = good engine/ preformance.
BP ultimate 98
Blend oils are shite,,,,,,,,,,,,
If you have no lumpy carbon build up, its a good oil.