Gerry H wrote:So my 20L can is about good enough for the lawn mower :roll:
I'd put a detalarm on the lawnmower if I were you :-D
Seriously though, we're talking small differences here. For sure, buy fuel as close to a race or trackday as you can and buy it from a station that has good throughput. Beyond that though, you'll always see some variance in pump fuel.
When I raced bikes it was commonplace to tune GP250 2-strokes to run on Avgas, but I've not heard of its use in cars (trackdaying and low key amateur racing at least). Similar RON/MON/AKI to methanol I think. Octane rating aside, it was regarded as more consistent than regular pump fuel with a similar price (whereas 'proper' Elf race fuel cost 10x as much). Supply was a bit tricky though, with airfields being choosy about who they'd sell it to!