Best gearbox oil

robs ss · Oct 30, 2021

I've done a bit of a search and believe the "best" gearbox oil (I'm due for a change) to be Dextron IV ATF.
Any thoughts to help?
Cheers

cliffa · Oct 30, 2021

Light blue touchpaper and retire to a safe distance....

Fast Eddie · Oct 30, 2021

This is the standard issue gear oil in my shed:

Anglophile · Oct 30, 2021

red line heavy shockproof gear oil

MexicoMike · Oct 30, 2021

Any gear oil that meets the OEM specs is safe. ATF MIGHT be OK but since ATF existed when Norton Commandos were made, one would think that if ATF was best, it would have been spec'ed by Norton.

SteveC · Oct 30, 2021

Why not just use EP80W-90. I use the castrol version and seems to be OK. I always thought ATF was for automatics?

maylar · Oct 30, 2021

alan hodge · Oct 30, 2021

red line heavy fo me

olympus · Oct 30, 2021

robs ss said:
I've done a bit of a search and believe the "best" gearbox oil (I'm due for a change) to be Dextron IV ATF.
Any thoughts to help?
Cheers

I've been using Dextron II for the last 1000mls, the gear change is as slick & as light as you'd like with no noticeable gear noise
I have just drained it as part of the my annual maintenance program and there is no silver sheen to the oil with nothing on debris magnet
New Dextron II have been added

olympus · Oct 30, 2021

SteveC said:
Why not just use EP80W-90. I use the castrol version and seems to be OK. I always thought ATF was for automatics?

Manufacturers have used ATF for years in manual boxes

MexicoMike · Oct 30, 2021

FWIW, ATF is the standard fill for various automobile manual transmissions. But that doesn't make it appropriate for the Norton transmission. It depends on the design of the transmission.

I tried ATF in the Norton a few years ago out of curiosity and found the shifting to be less smooth/more clunky with missed shifts so I removed it after one 250 mile ride.

mean gene · Oct 30, 2021

Chrysler recommended ATF in their 4 speeds. But in my Norton's that are prone to leak I use Bel Ray. Bel Ray saved my butt on a trip when I had a bearing going bad. It was a weekend and had to ride it till I got to a Harley service center! For absolute lost of horse power the ATF would be best.

Onder · Oct 30, 2021

Perhaps the ATF is better for the sleeve gear but less so for oil leaks.

seattle##gs · Oct 30, 2021

Anglophile said:
red line heavy shockproof gear oil

I have used the shockproof oil in my Norton box but I worry about the oil's ability to get in on the mainshaft/high gear bushings. The heavyweight shockproof oil might be too thick to flow in and out of that area. So I use ATF. I don't notice any difference in shifting with either shockproof oils or ATF. The blue lightweight shockproof might be better and I know it works well in the old BMW R60/2 "crash boxes"...by the way, it really does improve shifting in those old clunkers.

Fast Eddie · Oct 30, 2021

I’ve got some quarts of lightweight Redline shockproof gathering dust.

I used to use it. But I tried some different oils a while back and the Bel Ray gave the smoothest shift, best neutral selection etc.

Just ‘feels’ more lubricating to me.

It’s also compatible for wet clutches, so IF it did find its way in to your clutch, it ain’t gonna cause issues.

robs ss · Oct 30, 2021

Fast Eddie said:
I’ve got some quarts of lightweight Redline shockproof gathering dust.

I used to use it. But I tried some different oils a while back and the Bel Ray gave the smoothest shift, best neutral selection etc.

Just ‘feels’ more lubricating to me.

It’s also compatible for wet clutches, so IF it did find its way in to your clutch, it ain’t gonna cause issues.

Okay - you got me!
I'll try some of that.
Cheers

gortnipper · Oct 30, 2021

Fast Eddie said:
I’ve got some quarts of lightweight Redline shockproof gathering dust.

I used to use it. But I tried some different oils a while back and the Bel Ray gave the smoothest shift, best neutral selection etc.

Just ‘feels’ more lubricating to me.

It’s also compatible for wet clutches, so IF it did find its way in to your clutch, it ain’t gonna cause issues.

Yeah but you breathe the rarified air of those with a TTI box.

Fast Eddie · Oct 30, 2021

gortnipper said:
Yeah but you breathe the rarified air of those with a TTI box.

Tis true, but I also use it in my Triumphs and other old shite.

Schwany · Nov 2, 2021

Fast Eddie said:
I’ve got some quarts of lightweight Redline shockproof gathering dust.

I used to use it. But I tried some different oils a while back and the Bel Ray gave the smoothest shift, best neutral selection etc.

Just ‘feels’ more lubricating to me.

It’s also compatible for wet clutches, so IF it did find its way in to your clutch, it ain’t gonna cause issues.

Does that Bel Ray fluid have a distinctive "red" color like ATF?

Fast Eddie · Nov 2, 2021

I think so, can’t remember !