Gearbox oil

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Without starting an oil debate what is the opinion on the best gearbox oil?
And also the best available in the UK if possible?
What are people using
Cheers
 
Just bought Castrol Axle EPX 85W-140 GL5 Multipurpose Axle Oil / Diff Oil - 5 LITRES 5L GL-5
will go in the TTI and my other 5 speed in the Interceptor. Probably will use it in the T150V
and the Albion as well. Only the Albion has bronze bushes in it.
 
I have read, probably somewhere on this site that GL-5 is not good for "yellow" metal i.e. gearbox bushes etc. GL-4 is preferred. I may be wrong in which case I am sure some one will chime in to point that out.
 
oldbeezer said:
I have read, probably somewhere on this site that GL-5 is not good for "yellow" metal i.e. gearbox bushes etc. GL-4 is preferred. I may be wrong in which case I am sure some one will chime in to point that out.
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Yep this is the reason I am asking
And the fact that I'm a complete amateur when it comes to understanding oils!
For example why shouldn't you use ordinary 20/50 motor oil in a gearbox?
 
Frankly, for the Norton I use whatever brand gear oil I see on the shelf when I need gear oil. Never seen/felt any difference between them. I tried ATF once for about a week but the shifts weren't as "buttery-smooth" as with gear oil so I went back to gear oil.

Motor/gear oils use different additives. Motor oil has to deal with combustion products while gear oil has to deal with the "crashing together" of gears meshing. Obviously oil that can do both isn't really a huge problem since most motorcycles nowadays have the engine and transmission in a common case, sharing the same oil.

Contrary to the viscosity spec on the container, gear oil is not thicker than motor oil. For example, at operating temp, 80wt gear oil and 20 wt motor oil are the same viscosity. It is said that back in the day, SAE decreed there be a difference in viscosity labels to ensure that people didn't select the wrong oil - put gear oil in the engine and visa versa. IOW, if they walked in looking for 30wt motor oil, they didn't accidentally pick up a "30" wt gear oil. Makes sense but I have no idea if it's true.
 
MexicoMike said:
Frankly, for the Norton I use whatever brand gear oil I see on the shelf when I need gear oil. Never seen/felt any difference between them. I tried ATF once for about a week but the shifts weren't as "buttery-smooth" as with gear oil so I went back to gear oil.

Motor/gear oils use different additives. Motor oil has to deal with combustion products while gear oil has to deal with the "crashing together" of gears meshing. Obviously oil that can do both isn't really a huge problem since most motorcycles nowadays have the engine and transmission in a common case, sharing the same oil.

Contrary to the viscosity spec on the container, gear oil is not thicker than motor oil. For example, at operating temp, 80wt gear oil and 20 wt motor oil are the same viscosity. It is said that back in the day, SAE decreed there be a difference in viscosity labels to ensure that people didn't select the wrong oil - put gear oil in the engine and visa versa. IOW, if they walked in looking for 30wt motor oil, they didn't accidentally pick up a "30" wt gear oil. Makes sense but I have no idea if it's true.
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EP: extra pressure, ie between gear teeth.
 
Since posting this question I have seen there are quite a few posts about the subject already!
I guess I will just stick with ep90 as I'm still not sure if anything else is better
 
From Redline

"Red Line D4 ATF is a popular choice for automatic transmissions as well as manual transmissions.

D4 ATF also provides a GL-4 level of gear protection, giving it balanced frictional characteristics that provide smooth and consistent shifts for extended drain intervals."

Many synthetic ATF's meet GL-4 specs.
 
Posted this earlier somewhere, ep90 for 40 odd years and first gearbox strip was last winter due to worrys about the dreaded layshaft bearing. Need not have bothered. I have always put a bit of molyslip in for good or bad. 650 but basically the same box, pulled a chair for a couple of years in the late 70s too. Ade
 
PRO: I use Redline MTL in a vehicle with a transaxle and it works better than other well-known products as far as smooth shifting. So I like Redline - at least that product.

CON: Their marketing people are working overtime in that white paper:

"The LightWeight can be rated as a 75W140 Gear Oil, but has the lower internal fluid friction of an SAE 30 motor oil. The SuperLight can be rated as a 70W90 Gear Oil, but has the lower internal fluid friction of an ATF"

Everybody's 75W140 gear oil has "lower internal fluid friction" (clever marketspeak for 'viscosity') than 30 Wt motor oil. Everybody's 70W90 gear oil has the viscosity of ATF. RL are using a simple fact about gear oil vs motor oil viscosity ratings and making it sound like they have done something clever in formulating the gear oil. ;)
 
just a thought. does everybody start and ride their bike the same?
I personally ride off as soon as I fire her up, then take it easy for a couple of miles. others ride gently all the time. then others wring the grannie out of it from start up. how does this equate with the best oil question?
 
Pushed it n rode it said:
Posted this earlier somewhere, ep90 for 40 odd years and first gearbox strip was last winter due to worrys about the dreaded layshaft bearing. Need not have bothered. I have always put a bit of molyslip in for good or bad. 650 but basically the same box, pulled a chair for a couple of years in the late 70s too. Ade
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I have found that Molyslip gearbox additive makes a noticeable difference to the smoothness of gear changing on many, many Brits bikes I’ve tried it in over the years. I’m a convert.
 
Fast Eddie said:
I have found that Molyslip gearbox additive makes a noticeable difference to the smoothness of gear changing on many, many Brits bikes I’ve tried it in over the years. I’m a convert.
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Is that available this side of the pond?
 
freddie1105 said:
just a thought. does everybody start and ride their bike the same?
I personally ride off as soon as I fire her up, then take it easy for a couple of miles. others ride gently all the time. then others wring the grannie out of it from start up. how does this equate with the best oil question?
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I start the bike and ride off straight away
 
freddie1105 said:
just a thought. does everybody start and ride their bike the same?
I personally ride off as soon as I fire her up, then take it easy for a couple of miles. others ride gently all the time. then others wring the grannie out of it from start up. how does this equate with the best oil question?
Click to expand...

I also like to start and get gently away asap, EP90 with a twist of Active 8;)
 
Fast Eddie said:
I have found that Molyslip gearbox additive makes a noticeable difference to the smoothness of gear changing on many, many Brits bikes I’ve tried it in over the years. I’m a convert.
Click to expand...
I have never used any of those additives ,I just consider them to be snake oil
Maybe I'll take another look at them
 
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