Oil classes

[TygerTung]

In the haynes manuel for my honda CG110, it recomends the use of 10w40 class SE or SF, now is it alright to use for example class SJ? I have just rebuilt the motor about 500km ago, so it's just run in.

SJ is designed for cars 1997+ it says in this magizene, and SE is from 1971-1979, and SF is from 1980-1988. It's an old manuel from the 80's so maybe they didn't know about SJ oil then.

Surley a newer oil would be better right? Or should I use the older oil?

The dude at BNT said I had to use special motorbike oil or it causes the wet clutch to slip.... Is this true?

Cheers,

Sam

[XTC]

Use SG or under. Anything higher has friction modifiers that may cause the clutch to slip. You will see that all motorcycles are SG or less.

[Krusti]

The dude at BNT said I had to use special motorbike oil or it causes the wet clutch to slip.... Is this true?

Cheers,

Sam

Yeah dont use oil with friction modifier, did it once in an emergency when I had my Bandit. Not good riding with slippy clutch!

[pritch]

Just be careful that the newer oil doesn't contain "friction modifiers". I think that's what they are called. Motobike clutches don't like friction modifers

[vifferman]

The codes are not really 'classes', as such - they represent API test categories (see http://www.infineum.com/information/api-passenger-sj-sl-2004.html )

As each new test category comes out, previous ones become obsolete. All you need to worry about is that the viscosity of the oil you choose is appropriate for the conditions, that you change your oil at the recommended intervals, and don't use some cheap crap. Oh yeah - and don't be sucked in by the advertising claims made.
There may be some problems with oils that are labelled "Energy Conserving" as they have 'friction modifiers' such as molybdenum compounds added. However, all oils have various additive packs, and whether these so-called 'friction modifiers' actually cause clutch slippage problems seems to be almost entirely anecdotal. Some recent stuff I've read (also anecdotal) said that the 'friction modified' oils were fine in wet clutch engines.
I'd made a habit of always using Motul semi-synthetic in my bikes, but recetnly I started using Shell semi-synth as it is signiificantly cheaper. I have read evidence (from an oil engineer who works as a consultant for the Murkn petroleum industry) that the best oils in terms of price vs. performance are oils for diesel engines, such as Vanellus, Rotella and the like.
I'll just keep using whatever makes me feel good.