2 stroke oil recommendations

[Keo]

Good Evening, can anyone advise the recommended 2 stroke racing oil for a Silverstone race bike please.....I've just re-assembled the machine and would like to get it running this weekend. I'll be using a 50/50 fuel mix of Avgas and Shell super with a 20/1 oil mix.

thanks in advance

[johnrunnacles]

I don't have experience of running a Silverstone myself but I do have the Villiers Singles Improvements Handbook published by Rob Carrick and John Wood. To quote: "Both authors use Castrol R40 or Morris MLR40 at a ratio of 25:1 as a lubricant, not because they are traditionalists, but because it is the only oil they have found to cope with the rigours of racing a heavily tuned 197 or 250 .............. Use of synthetic oils in modern liquid cooled motors is recommended, but not, please, in 30 year old motors ............... "

Hope this helps?

[Stan Nicholson]

I agree completely with Carrick and Wood. I have always used Castrol R in my race 2-strokes, at 20:1 ratio. In his book "Performance tuning in theory and practice, two-strokes" A. Graham Bell goes into some detail about lubrication and states: "In all of my competition engines, I specify Castrol R40 or R30 castor oil (R40 for air-cooled engines, R30 for water-cooled). This oil provides the best anti-wear protection of any oil I know." He goes on to say that not all castor oils are as wear resistant as Castrol R, depending on how well the manufacturer de-gums the basic castor stock and what additives are used and that some castors provide wear protection no better than average mineral or synthetic oils.

It is true that castor oil is hygroscopic, even after mixing, and that pre-mix more than 3 days old should not be used, but in my 45 seasons of road racing I have never found any corrosion when stripping down my motors, just a uniform oil coating over all internal parts. The other claim against R is that it gums up rings and causes ring sticking but, like Bell, I have never found this in practice. As for water absorbing, in my experience this isn't a problem and here in Canada we can get +10 deg to -20 deg C swings in a 24 hour period and unless the bike is stored in an unheated garage that means condensation will form both externally and internally this has not been a problem. Although my workshop is unheated during the winter, except when I am working out there, it is very well insulated so the temperature changes take a longer time and hence condensation does not form on any metal parts (including on my lathe!)

I would highly recommend getting a copy of Bell's book if you can, as it is a mine of information on tuning and running competition two-strokes.

Stan