- Thu May 10, 2012 9:03 am
#12332
Just a couple of extra thoughts. If your engine is fitted with a roller bearing big-end, I would choose straight non multigrade oil. Mr H sells Chatsworth (30 & 40 grade) or even Hardwick (50) for summer use with a tuned or large capacity conversion. My thoughts are that the roller big end is the most stressed bearing in the engine where roller have enormous pressures and are prone to skidding during their rotation. Multigrade can suffer molecular shearing (viscosity is reduced) so if the oil does not contain these viscosity improvers then they don't break down. With the roller bearings "open" construction excessive oil pressure is also less likely when the engine has no relief valve fitted, but the correct grade should be chosen to match the ambient air temperature (Winter Summer grades) and gentle use must be maintained until the oil has warmed sufficiently. As regards temperature, one should also aim to get the oil temperature up to around 70-80C to drive off water vapour and other fumes picked up in the oil. This is where the Enfield engines score well over engines that have separate remote oil tanks as their engines directly heat the oil tank by conduction. If you have regular short trips then you might try a lower level of oil as it will warm up faster and the “mayonnaise†problem will be reduced substantially. Don’t forget the oil feed to the engine is at the bottom of the tank and not half way up. However if you have strict oil mileage change routines then you must factor in that half the amount of oil circulating is doubling the usage of that amount oil so you might choose to change the oil more frequently (half the mileage) to match the reduced amount. However as the oil is now working at the correct higher temperature one could easily argue that the oil life has been extended by quite a bit (A big reduction in acidic water circulating) so one could achieve the same mileage from a lesser amount of oil, perhaps reducing wear and saving money at the same time ……. .. Just as an extra note, the anti-wear additive ZDP is most likely to be found in API grades SF or SG as after that the later API grades had to use a reduced amount for environmental and catalytic converter reasons….whether the later API grades are suitable in old style engines, one can read totally opposite opinions, so make your own informed choice. Just my thoughts and my thoughts ONLY. One should do as one thinks best themselves after carefully taking in all the facts.
