From the Victa website regarding the Formula V 2 stroke oil:
Valvoline and Victa worked together to develop a range of
high-spec synthetic fortified oils that protect your mower�s
engine far more effectively than standard mineral-based
products. Using high-performance Victa Formula V oils
maximises your engine�s power output and optimises its
working life as well.
I think the key point is that Formula V is a reduced friction, semi-synth oil as opposed to mineral-only regular 2 stroke, thereby allowing a 50:1 mix to be used safely in Victa 2-strokes. Valvoline also have a standard mineral 2 stroke in their range which needs to be used at the 25:1 ratio.
Interestingly, I remember the Victa Twin 170cc and Lightweight 85cc engines were set up to run a 50:1 mix on normal 2 stroke. Why was that? Was it the comparatively small component sizes? If so, then why do 30cc whipper snippers often use the 25:1 mix?
