13-08-13, 04:46 AM
(12-08-13, 07:13 PM)dickturpin link Wrote: my manual gives a range of viscosities and states oil must be API grade SE SF SG or higher. My last oil change was a Castrol mineral oil to API SG. So whilst I'm not saying semi synth isn't better, but aren't we getting OTT when Mr Yamaha's recommendations are within the grades available from mineral?
Discuss.....
D
First, those are minimum requirements. Say you live in deepest Wogga-Wogga and can't get latest top-spec oils, the bike will still run OK on dinosaur juice. You just need to change it more frequently.
Why? Well, it's down to how long the oil retains its viscosity and ability to protect against wear, particularly how well it resists shearing within the gearbox. A dino oil and a fully synth will give the same protection for, say, the first 1000 miles but after that the dino stuff starts to break down faster. The additives in the fully synth prevent that happening so the fully synth is still performing at close to original specs for many thousands of miles longer.