Upper cylinder lube.

Robert, Gordon J has a lot of experience in the long term effects, if any of using 2 stroke oil in a 4 stroke's tank.

I only use E0 petrol but I do put a bit of Redex led substitute and caster oil for the aroma in my tanks. Never done any harm to date.

Some 2 strokes will run on a 200:1 mix whilst 100:1 is usual these days. 200:1 is probably a bit on the oily side for a 4 stroke engine. I go for approx 200:1 in the 1913 Douglas with its somewhat primitive lubrication system but for the others just a tablespoon to a tankful of petrol - approximately 500:1. Not enough to cause plug oiling but hopefully enough to give a little protection to the petrol tank, carb and inlet valve guide.

All a bit unscientific but so far it seems to help protect the bikes from some of the worst effects of ethanol in petrol.

In the Olden Days we used Redex at the pumps. It made you go faster, louder, better economy and better in bed! (Scrap the last one!)

A little aircraft red hydraulic oil, added to 140 octane aviation fuel, served two purposes.

1. Upper cylinder lubrication.

2. Changed the fuel colour, from green to muddy brown (which fooled the service police!).

I take it you were not caught John. Many years ago I managed to intercept one of my airmen who was on his way to "borrow" some of her majesty's petrol for his bike knowing that the RAF SIB police were waiting in ambush. A forceful quiet word saved the day and his career.

P.S. did you ever get plug whiskering with the 140 octane?

Hi Gordon, no, I didn't get caught. A couple of mates, who couldn't be bothered with the camouflage, got 28 days! As for plug whiskering, no, it never happened using a gas, the only time I experienced it was many years later, with a Japanese 2 stroke.