As an example, Nissan specify a GL4 gear oil for the SR20DET gearbox.
I have previously used a GL5, but will now convert back to a GL4 after reading this:

http://www.widman.biz/uploads/Transaxle_oil.pdf

Very interesting document on why GL-4 is better for synchromesh than a GL-5 oil.
GL5 oils should be better for Extreme pressures (not necessarily in a gearbox, but in a differential) and may reduce wear on the gearbox gears themselves, but the synchro's will wear to death and notchy gear changes will be yours forever.

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1972 Datsun 1600, S14 SR20DET Engineered (204rwkW @ 17psi.)
viewtopic.php?t=6579
#SR20Datsun @SR20Datsun

Yup. I read the same thing about 6 months ago. I run GL-5 also but will change back when i can be bothered. (Car doesn't run enough). Interesting that the additive corrodes the synchro's. I have noticed that my gearbox isn't all that smooth and tends to catch until its warmed up. I thought it was due to the oil weight.
Probably more likely to the type of oil instead!
I think I run GL-5 oil in my diff also, Open centre R180.

_________________
Ongoing Project: 1972 Datsun 510 S13 SR20Det. http://ozdat.com/forum/viewtopic.php?f=33&t=17898
New Daily: D22 Navara (The new workhorse)
Retired 12/2016: MY98 Subaru Impreza RX
Previous Car: Restored Green 1972 Datsun 510, Hot L18

The GL-5 should be run in the differentials due to the EP additives. No change there!

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1972 Datsun 1600, S14 SR20DET Engineered (204rwkW @ 17psi.)
viewtopic.php?t=6579
#SR20Datsun @SR20Datsun

What brand of GL-4 do you recommend? I need to fill my SR gearbox up with oil as it leaked out of the rear seal when the driveshaft was removed which is oh so common hahaha.

Cheers,

Richard

How many years have I been trying to convince people not to use GL5 or universal gear oil.
Any oil that contains EP additives or thyohypoid

Normal engine oil is much better in Nissan boxes than GL5.

I am sure I first mentioned this on this forum at least 12 or more years ago.
We were aware of the problem back in the 70s.

I must have advised 1000s of Nissan owners over the years. Not to use universal gear oils in Nissan boxes.
Obviously this has fallen on deaf ears..

I have also said that a mix of dexron3 & manual trans oil is good for the baulk ring synchros in Z & K boxes.

http://ozdat.com/forum/viewtopic.php?f=2&t=32

http://www.ozdat.com/forum/viewtopic.ph ... L4#p257814

http://www.ozdat.com/forum/viewtopic.ph ... il#p139861

_________________
A little knowledge is a dangerous thing.
www.datsport.com

"R.I.P. Baz. 29 April 2022. Thank you for all your contributions to the Datsun community over the years. You will be missed." - OZDAT

The attached documents are from Mr Nissan's manual.
A search of the internet shows that Mr Nissans requirement for API GL-4 with a viscosity of 75W-90 may not be easily found.
Seems that every oil company has GL4 75W-85 which would be OK for many uses, but their 75W-90 is GL5
The only API GL-4 75W-90 I found was this http://www.hi-tecoils.com.au/product/ge ... l-4-75w90/

I am using this
http://www.liqui-moly.com.au/workshop/p ... gl4-75w90/

with a bit of this added
http://www.liqui-moly.com.au/workshop/p ... -additive/

The S14 5 speed in my car was fairly notchy when I got it back on the road but a change to the LiquiMoly has transformed it.
It now shifts beautifully.

Nup. Only just got around to an oil change in the gearbox and wanted to know which oil to use. I distinctly remembered you mentioning it a while ago Baz, which lead me to posting the post above for everyone as a 'refresher'.

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1972 Datsun 1600, S14 SR20DET Engineered (204rwkW @ 17psi.)
viewtopic.php?t=6579
#SR20Datsun @SR20Datsun

Interesting.
I'm going to be running the Pro Gear 75W-85 GL-4+ from Penrite.
Do you (or anyone else) know what the difference between GL4 and GL4+ is?
I'm also going to be running a temperature monitor on the gearbox, so not too worried about track days.
What colour was the gear additive?

_________________
1972 Datsun 1600, S14 SR20DET Engineered (204rwkW @ 17psi.)
viewtopic.php?t=6579
#SR20Datsun @SR20Datsun

What oil do you use SR20DATSUN?

Cheers,

Richard

I was running the Pro Gear GL-5 75W-90. I only had it in the car for a few track days. It performed very well once warmed up, but cold it is notchy as hell..

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1972 Datsun 1600, S14 SR20DET Engineered (204rwkW @ 17psi.)
viewtopic.php?t=6579
#SR20Datsun @SR20Datsun

Don't know what the plus indicates, the additive is dark grey, guessing it is some sort of moly based compound.
I use their engine flush at every oil change too.

I've been running Liqui Moly stuff for about 6 years now, spoke to a few race engine builders who couldn't speak highly enough of their products.

Then a mate started working for the importer so I get it dirt cheap.

I use it in everything, engine, gearbox and diff for all our cars which includes everything from my wifes Mk5 GTI Golf, my SR20det, to my TD42 GQ Patrol. I even use it in my Volvo 240 and my Valiant 318.

Great stuff, can't recommend it enough

The attached document is from the API
Would seem that API GL-4 stands for American Petroleum Institute - Gear lubricant type No 4
API are the organisation that make the lubricant standards.
The standards document doesn't list a 4+ so I assume that the manufacturer has adhered to the standard to a point, but not completely. If you look at the bottle of Moly turbo 510 is using, it states GL4 (GL4/GL5) so it looks like some kind of hybrid.
There are a number of lubricant manufacturers that market GL-4 + and make the statement ''won't damage yellow metals'' which is why we are talking about the perils of GL5 lubricants in the first place so it is probably fine. (maybe)
turbo510 could you ask your Moly contact what the label on their bottle really means.

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1971 Datsun 1600 http://ozdat.com/forum/viewtopic.php?f=59&t=34174

I'll try to find out, I just checked the bottles I have in the shed (I buy a 10 pack of 1L gearbox or diff oil and 20L Engine oil at a time) and the stuff I have has a different label with just GL4 on it.

It is a year or so since I bought gearbox oil so they may have updated the product/label