[M John Galt]

The issue isn't with what percent VO a hot engine will run on, but rather about the damaging engine deposits which form when VO-ULSD blends greater than 25% are used to cold start a cold engine. As well as the problem with unburned VO depositing on injectors, piston tops and rings, there is unburned VO diluting the engine oil. VO in engine oil can increase polymerization of the oil, reduce oil flow and damage bearings.

This is why most people recommend using a two tank SVO system for high percent blends, with the possible exception of older indirect injection engines like MBenz and B & H series non-turbo Toyotas, which are more tolerant of higher percent VO blends.