23/12/2019
Engine oil has six main purposes:
Lubrication
Cooling
Sealing
Cleaning
Corrosion protection
Reducing noise
Not all friction is the same – some’s easy to deal with, and some is really tough on oil…
Sliding friction: You’ll find this between the piston rings and the cylinder as the piston moves up and down.
Rolling friction: This occurs in ball bearings for instance.
Combined friction: This is found in gearboxes, and it’s the most demanding on oil. This environment is harsh too, as the gears’ teeth roll and slide over each-other at extremely high pressures on a single point; it’s why cars use a different oil in the gearbox to the engine, and the first clue as to why you should not use car oil in a motorcycle.
A good quality oil with have a polar base and additives that leave a thin coating on the engine’s internal surfaces, to reduce wear at start-up. But the colder the ambient temperature is, the longer it’ll take for the oil to get around the engine. Thrashing your bike from the moment it’s started is going to damage it – I usually fire it up, then put my gloves on, and ride away gently.
Ester, which comes from plants and other living things – it’s not refined from crude oil. Ester is the best base oil, but it can’t be used on its own; some brands will claim their oil is 100% ester, but that’s only the base oil; without additives, it won’t work in an engine.
Ester’s got an even higher Noack value, the molecules are naturally attracted to positively-charged metal surfaces to create a protective film, and it’s more biodegradable. But it needs additives to prevent it ruining the seals in your engine, and it’s expensive.