HOME and how to join Forum Open Area General Scott topics Adding paraffin to petrol. Re: RUNNING ON PARAFFIN?

David J Waring

Your observations are very interesting, although I suspect that you both have a better sense of smell than I, Brian & John!
From my experience of pre war & vintage cars, I am sure that the Bentley would run on petrol with some paraffin added, but with such cars in the “price upon application” class, I would doubt that the owner would risk it, and think that stale petrol is the more likely answer.
Lesser 4 stroke low compression engines (e.g. side valves) would run on such a mixture, and possibly run on paraffin alone on a hot summer’s day, if warmed up on petrol first. However, there would be unburnt fractions, which would settle on the pistons, pass the rings and dilute the sump oil, unlike a 2 stroke*, which stands a chance of ejecting the fractions to exhaust.

*This is based on personal expeience, when as a 15 year old, I ran an old air cooled 2 stroke around the garden on hot household paraffin (Aladdin Pink), by starting up on petrol, then switching to an auxiliary tank, from which the paraffin ran in a copper pipe wedged in the engine cooling fins to deliver it hot to the carburettor. The engine ran reasonably well on this preheated fuel, although unburnt fractions of the paraffin emerged as a black liquid from the exhaust. Examination of the crankcase showed some build up of the black liquid, but the two stroke appeared capable of dispersing most of it, so continued to run and receive some lubrication. The only thing to remember with the paraffin was to switch back to petrol before stopping for any length of time, as restarts on paraffin were only feasible if still hot. (Full story in Yowl Dec 2011)