On Wed, 29 Mar 2006 18:32:39 GMT, dave wrote:

Just want to replace the transmnission oil (all 0.11L of it) in a 2 stroke
scooter. The book say use 10/30 SE oil in the transmission. Can't find any oil
in the mighty Halfords that has the SE bit at the end.

Is SE the same thing as EP (Extreme pressure)?

Not at all. EP is for use with hypoids back axles which have sliding
contacts that generate "extreme pressure" contacts. This needs a lot of
extra additives in there which aren't a good thing for general oiliness.

In particular, EP oils can destroy some bronze components, particularly
gearbox dogs and synchro rings. Don't put EP somewhere that doesn't want
it, you really might break something.

"SE" is a quality rating, mainly for expected lifetime in hot engines.
SE oil can be replaced by SF, SG, SH, SI etc. - each grade being
progressively better. You don't need these good heatproof oils in a mere
transmission. It's getting hard to find the lower S ratings though!

Don't use synthetic oils in things that didn't always use them, or don't
need them. Synthetic oils have ligh lubricity and will tend to leak
through oil seals that were perfectly adequate with mineral oils.
They're good in modern, clean engines, but a risk of trouble in other
things.

On any motorbikes, always follow the maker's recommendations. You
probably have a wet (oil-bath) clutch in there and it's fussy.