SPENGILLY wrote:Bel Ray synthetic for the last 5 or 6 years. Before that I used a havoline non synthetic that I was getting for free. I was told back then by a mechanic at my work that the non syn. would lubricate better. Don't ask me, that's what I was told.

Non synthetic - if that's mineral oil, it is indeed an excellent lubricant but not at extremes of temperature. At higher RPM, therefore higher temps, the oil will thin, lose boundary lubrication, metal to metal contact & engine seizure.

If its Castor oil, again very good lubricant, higher shear strength and anti-wear properties than mineral oil, but it burns dirty (resin / varnish deposits) and gums up at high temps. Used to be used a lot in 2T race engines, if loaded with anti-oxidation additives and engine stripped & cleaned regularly, smells nice - Castrol R!

Modern Fully synthetic 2T oils are all Ester types, high shear strength (good boundary lubricants), much greater viscosity stability at extremes of temp. Most of these oils from leading manufacturers (Rock Oil, Silkolene, Castrol, Motul etc etc) all use the same base stock ester oils, but their chemists will have played around with different additive packages.
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Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30