Which Transmission oil

[sveson]

The manual recommends 0W75 Gear trans oil, but I cant find that oil anywhere. What are you all using?

[heffergm]

75W wet clutch gear oil is pretty easy to get. I see you're in Sweden, so I'm not sure what you have easy access to, but a few options would be:

- https://www.motosport.com/silkolene-light-gear-oil

- https://www.motosport.com/maxima-mtlxl-transmission-oil

- https://www.motosport.com/belray-75wt-gear-saver-transmission-oil

 

I'm sure plenty of people, as with the GG and TRS, run ATF as well.

[sveson]

Thank you for your answer. But isnt there a difference between 0W75 and 75W oil? Yes, I live in Sweden so maybe its harder to find the right oil. 

I put ATF oil in the bike and after that I think the clutch has gone harder so now I want the right oil. 

[peterb]

Hello sveson, the Spanish factories tend to use a fully synthetic 75W oil in the clutch/gearbox. The "W" stands for winter. Various companies can supply this oil, I am not sure what is available in Sweden, but some of the more familiar ones are GRO, Rock oil and Castrol. I have used ATF for well over 25 years in all sorts of bikes without any problem, always ATF rated to Dexron III. All of the Jotagas here run with ATF. Is it possible that you have had water in the gearbox? Although not a common wear point on these bikes, the water pump shaft/seal may have worn. Bye, Peter B.

[peterh]

I have taken a bit of interest in transmission oils and the potential influence on clutch action, cold grab, lightness and/or aggressiveness and then related those to viscosity and viscosity index while also respecting lubrication of other rather important parts and bearings. I have tried different oils and listened and read of others experiences and 'gospels'. I have constructed a spreadsheet and sorted by viscosity at 40°C (see pdf attached) from manufacturers specifications (some are hard to track down) and then found a website (see the link on the 2nd page of attached pdf) where you can plot the change in viscosity with temperature - with pictures put into the pdf. Another link on the 1st page of the pdf explains Viscosity Index and it seems to me that for trials where great variations in speed, load and temperature exist perhaps a high Viscosity Index (VI) oil would be appropriate to maintain the optimum viscosity (if we even have any idea what that would be). For my style of riding (no instantaneous huge splat walls) I like progressive and light clutch action in my 2015 Jotagas 250 and I like to change my oil every 10 hours, so I also like to look at price comparisons for similar viscosities and viscosity index. Of course there is no perfect answer as we are all different in our riding ideals but maybe this sheet might give you something more to ponder and try. There are oils on the list that may not be available where you are, in the same way some on the list I cannot get downunder and haven't tried them. If interested, I use Chief Oil's - Mohican ATF Dexron III (and buy 4L for less than the price of 1L of some other oils on the list). But I am no oil expert and none of the above is validated for viscosities and temperature and thus it is all just my thoughts and experiences and certainly not challenging the manufacturers - or the oil experts. So whatever works and is available for you, works for you; in the same way that what I use and have available works for me. 

Gear Oil comparisons.pdf

[peterb]

Well researched and written peterh, I also have used Mohican ATF Dex III to good effect with similar change times.

 

[Darcy Sarto]

Used Rock oil gear pro 75 in my 2013 Jotagas. It was very good as I remember. GRO gear extreme has very good spec's and is similar to ELF HLX 740 if not better, which I now use in a Montesa 4rt, as hard to get the ELF. The Montesa's are sensitive to poor gear oils, they show up when the engine is cold and the clutch drags or the plates sick together for the 1st 30m! No problems with the GRO, very good clutch feel from cold, easy to get and not to expensive. Oil is your best mechanic.