Any of you UK scribes old enough to remember the days when every garage had a Redex dispenser by the pumps ? A couple of squirts per gallon provided upper cylinder lubrication for the petrol 4 stroke. Acquired such a dispenser around 60 year ago filling with diesel for the same purpose and many a mile later on the '55 250 BSA, '64 200 SS Ducati and all that was to follow never had a problem, mind you those days ethanol use was as a paint solvent and disinfectant. Now that petrol and diesel contain ethanol the addition of diesel or old engine oil in the steel tank of a stored bike will help to overcome the hygroscopic nature of the ethanol rusting the tank's base weld.
Aye Chris, as an auld time hack I did indeed add a pint of petrol to a gallon of diesel for the LandRover. With winter temperatures frequently 20+ deg. C. below in the Cairngorms the diesel was like jelly and to thin the fuel further for lower temperatures I'd roll up newspapers to make a flaming torch to heat the underbody fuel line. Paraffin would have been the better additive, withstanding the compression bettor than petrol but not so convenient. Incidentally back then I flew control line model aircraft with a range of high revving 0.5 to 3.5cc diesels with a fuel mix of Ether, Paraffin, Castor Oil and a variable dash of Nitro Methane, all components from the village chemist but for the paraffin, from the garage, whose main purpose was for the Tilley lamps fired up during power outages.
Those were the days. I used to make a mix just like that to run a tiny diesel RC aircraft engine, the proper diesel (not the glow-plug one which is also technically a diesel) with the compression adjuster you used to back off once it'd started.
I always used to put a small amount of fully synth oil in the petrol tank of my Ducati's back in the dim mists of time. No more than a table spoon or two. Never experienced a problem and it made me feel like i was doing the engine some good.
Used to run my old Isuzu fully on vegetable oil with no problems. But I would be very wary of any additives on modern common rail engines.
One of my mates used to put a shot of castrol R in his tank - could have been early ZX10 2004 or TL1000s. The smell was great when I was trying to keep up.
