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AO Gold Member
Join Date: Feb 2005
County: Down in the Park
Re: Oils ain't oils?
Frogman: What't the oiltemp of your engine like typically? If it's below 100°c a xw-40 oil will be fine, but if it's going up to 110-120°C I'd go for a xw-50 or 60.
To answer your other question: A good synthetic oil will be superior to a very good mineral oil, but as with anything you get what you pay for but no more...
With a synthetic oil there wouldn't be a need to change the oil every 5000km, unless you get an extremely wide viscosity range like for example a 5w-50. Due to shearing the viscosity would likely ddrop to 40 again after a few thousand km, and due to evaporation and burning the cold viscosity would likely go up to 10w or 15w.
The less cheap synthetics will have better quality dopes and in that case the oil would stay good for at least 20000 km.