gearbox oil?? castrol gtx r

[kevbn2]

Which is the best gearbox oil to put in my 350 N2
also i have drained all 2 stroke oil from pump back but not engine will i need to strip engine and clean to run mineral or can i just fill up new now or has the syn castrol R got the same properties and smell?
Cheers

[wonkywheel]

I'm using Silkolene light gearbox oil, seems ok on a standard gearbox.  Any designated motorbike gearbox oil will be ok. So Castrol will be fine. Stay clear of motor engine oils- too thick and contain additives which aren't kind to gearboxes. However, many members use different viscosity of oils, so opinion is a little divided. Just use a good motorbike brand.
 Bleed the pump with your chosen oil; let it tick over for a while, maybe take it easy for a few miles to let the new oil to circulate. Then away you go.

[bryan]

Use any light gear oil for gearbox with wet clutch, avoid fully synthetic as it will slip.
When changing 2 stroke oil, ideally get it all out to pump, bleed new oil through, start engine, remove the clip on the metal end of pump cable inside case and pull the outer all the way up to put pump at max stroke for a few min, will smoke a bit more but wil get any air through quickly.

[icarus001]

I'm using up the motocross engine oil I have left over, its £60 for 4 litres so its decent stuff.
Motorex 10w-60, its meant for 4T's but its for bikes with a wet clutch.
No problems yet but I change it every few hundred miles anyway and once its run out I'll buy a dedicated 2T gear oil.

I put Motul fully synthetic once in my Ducati and the clutch started to slip immediately.

[cooler]

i use atf in my box......works a treat....no slip and i can always get neutral

[whoisthatdc]

never tried atf obviously it must be ok

[whoisthatdc]

I have always used silkolene light gear oil never had a gearbox problem
plenty of others though it is an Lc after all

[Bozzy]

He often are you changing gearbox oil. Had mine in for just over year but only done 600 mls...oil looks clean? A little condensation only

[icarus001]

Jun 2, 2013 23:26:49 GMT 1 Bozzy said:

He often are you changing gearbox oil. Had mine in for just over year but only done 600 mls...oil looks clean? A little condensation only

You should change every year at a minimum.
Without going into technical detail the oil loses some of its properties after a period of time, even if its not used, hence why emergency generators and such equipment get an oil change every 12 months even if they haven't been used very much.

Changes in temperature kills oil, so lots of cold starts and short journeys will be detrimental, its usually the acidity (TAN level) that knackers it up, once the oil starts to turn acidic it very quickly goes off. TAN can be increased by temperature, contaminants (bits of clutch plate and wear metals) and age.

Another important point is that you should make sure you fully drain the old oil, perhaps even flushing it if your oil has a high TAN level. If you leave even a small amount in then it will contaminate the fresh oil and the whole lot will go off very quickly. I've seen oil fail tests after only 20hrs of use because the previous oil wasn't drained properly.

Personally in a two stroke with wet clutch I change mine every few months.

[Bozzy]

thanks taken your advice going to change it after tuesdays night ride out.

To be honest I would always change every year but with only doing low miles and gearbox only it would not be too much a problem. better be safe than sorry...

[icarus001]

I'm very tempted to try ATF, I've heard very good stories about it and I ran my lads KTM motocross bike on it for 2yrs and it was spot on, clutch lasted ages, no slip and the gearbox was like new when we split it.

Anyone else used it?