GL4 EP80/90

[Ralph Whitaker]

Went shopping yesterday for Hypoid oil for the rear axle. Extremely confusing as there were what seemed like hundreds of different gearbox and axle oils and I struggled to find any good old EP90. Finally settled on Rock oil EP 80-90 Hypoid Gear Oil.

However on getting it home and reading the extremely small print on the back that required my magnifying glass it says it is GL4 and choosing the correct grade is vital, and that Rock oil make GL1/2/3/4/and 5 and full spec is available on request.

Firstly, do you think this is OK for the TR back axle?

Secondly, you would think if it was that important the info relating to grades would be on the front of the bottle.

Thirdly, all the manufacturers seem to have done away with the flexy pull out spout, so getting it in the gearbox or axle is going to be fun.

Ralph

 

 

Edited June 20, 2021 by Ralph Whitaker

[Lebro]

GL4 is perfect.

Bob

[Phil Read]

I get all my oil supplies delivered from Smith and Allen. As I have a few old motors I usually buy 20lt https://www.smithandallan.com/products/agricultural-gear-and-transmission/1893-smith-and-allan-geartech-ep90---ep-90-hypoid-gear-oil-api-gl4-ep-90/

[ijonsson]

2 hours ago, Ralph Whitaker said:

Went shopping yesterday for Hypoid oil for the rear axle. Extremely confusing as there were what seemed like hundreds of different gearbox and axle oils and I struggled to find any good old EP90. Finally settled on Rock oil EP 80-90 Hypoid Gear Oil.

However on getting it home and reading the extremely small print on the back that required my magnifying glass it says it is GL4 and choosing the correct grade is vital, and that Rock oil make GL1/2/3/4/and 5 and full spec is available on request.

Firstly, do you think this is OK for the TR back axle?

Secondly, you would think if it was that important the info relating to grades would be on the front of the bottle.

Thirdly, all the manufacturers seem to have done away with the flexy pull out spout, so getting it in the gearbox or axle is going to be fun.

Ralph

 

 

I bought one of these, £25, ca pump or suck 1,5 litres

3197 (1360×1361)

[SpitFireSIX]

5 hours ago, Lebro said:

GL4 is perfect.

Bob

If GL4 is perfect then GL5 is??

[Hamish]

5 minutes ago, SpitFireSIX said:

If GL4 is perfect then GL5 is??

Is a change in formula that doesn’t agree with the yellow metals used in older cars. 

[SpitFireSIX]

21 minutes ago, Hamish said:

Is a change in formula that doesn’t agree with the yellow metals used in older cars. 

Are you saying GL5 cannot be used in Triumph diff & if you did it would be detrimental to its life?
If so, I disagree with you.

[Hamish]

That fine. Luckily we live in a free world. 

I didn’t say it can’t be used. I suggested it doesn’t agree with yellow metals used in older cars.
 

opinions differ and this leads to a richer life. 
 

Perhaps others will add there experience and knowledge either way. 

[RobH]

Although written for American cars, I think this explains the thing well:

https://www.rtsauto.com/wp-content/uploads/2016/12/Transaxle_oil.pdf

I've never taken one to bits but I guess there is no 'yellow metal' in the TR diff so expect GL5 will be OK?  But then again I don't believe there is any history of premature wear in the diff either, so GL4 must be quite adequate for it and probably rather better than the stuff which was used when the cars were new.  

[ijonsson]

23 minutes ago, RobH said:

Although written for American cars, I think this explains the thing well:

https://www.rtsauto.com/wp-content/uploads/2016/12/Transaxle_oil.pdf

I've never taken one to bits but I guess there is no 'yellow metal' in the TR diff so expect GL5 will be OK?  But then again I don't believe there is any history of premature wear in the diff either, so GL4 must be quite adequate for it and probably rather better than the stuff which was used when the cars were new.  

Thrust washers in the diff are bronze, but I don't know if bronze classifies as "yellow metal", or if was just brass that didn't agree with GL5

Edited June 20, 2021 by ijonsson

[SpitFireSIX]

The difference between a transmission & differential confuses a lot of people.

[RobH]

Yes bronze is yellow metal.

19 minutes ago, SpitFireSIX said:

The difference between a transmission & differential confuses a lot of people.

The paper discusses transaxles of course which includes both.  In think only those with poor comprehension will have difficulty with it.  As the author points out the GL ratings are for gear oil - not specifically hypoid oil so the discussion must cover both aspects to be meaningful. The reason why the oils attack yellow metal is well explained I think. 

Edited June 20, 2021 by RobH

[SpitFireSIX]

GL5 is fine in a diff & has more extreme pressure protection. How can GL4 be perfect?
What are these GL5 oils that are not suitable for A Triumph diff?
Penrite for example only seem to offer GL5.

[OWEN WB]

Typically, both GL4 and GL5 oils use the same sulphur/phosporous chemistry - and the type of that S/P chemistry dictates how aggressive it is to yellow metals. The GL4 treat rate of the chemistry will usually be half the treat rate of the GL5, thus the GL5 will be more aggressive without additional mitigating chemistry.

But the GL5 gives the greatest protection - and is the typical baseline requirement for an axle.

GL4 is a transmission spec.

GL4 oils will not meet the requirements of load bearing and extreme pressure wear that a GL5 oil will meet.

If its just a GL5 oil, it wont meet the synchroniser performance needed to meet GL4 because it will be too active.

But there are many oils that will offer both GL4 and GL5 performance - and anything with MT-1 performance will have yellow metal passivators in it.

 

[Ralph Whitaker]

I`m even more confused now than when I started.

Ralph

[DavidBee]

On 6/29/2021 at 4:37 PM, OWEN WB said:

Typically, both GL4 and GL5 oils use the same sulphur/phosporous chemistry - and the type of that S/P chemistry dictates how aggressive it is to yellow metals. The GL4 treat rate of the chemistry will usually be half the treat rate of the GL5, thus the GL5 will be more aggressive without additional mitigating chemistry.

But the GL5 gives the greatest protection - and is the typical baseline requirement for an axle.

GL4 is a transmission spec.

GL4 oils will not meet the requirements of load bearing and extreme pressure wear that a GL5 oil will meet.

If its just a GL5 oil, it wont meet the synchroniser performance needed to meet GL4 because it will be too active.

But there are many oils that will offer both GL4 and GL5 performance - and anything with MT-1 performance will have yellow metal passivators in it.

 

This is refreshingly technical. Thank you, Owen W B and begs the question as to what product/s you personally would feel confident to recommend for use in a TR differential?

[David Owen]

On 6/29/2021 at 11:37 AM, OWEN WB said:

Typically, both GL4 and GL5 oils use the same sulphur/phosporous chemistry - and the type of that S/P chemistry dictates how aggressive it is to yellow metals. The GL4 treat rate of the chemistry will usually be half the treat rate of the GL5, thus the GL5 will be more aggressive without additional mitigating chemistry.

But the GL5 gives the greatest protection - and is the typical baseline requirement for an axle.

GL4 is a transmission spec.

GL4 oils will not meet the requirements of load bearing and extreme pressure wear that a GL5 oil will meet.

If its just a GL5 oil, it wont meet the synchroniser performance needed to meet GL4 because it will be too active.

But there are many oils that will offer both GL4 and GL5 performance - and anything with MT-1 performance will have yellow metal passivators in it.

 

 

 

This is fascinating.

[OWEN WB]

15 hours ago, DavidBee said:

This is refreshingly technical. Thank you, Owen W B and begs the question as to what product/s you personally would feel confident to recommend for use in a TR differential?

Ha! That is a really good question! I have only just got back into old Triumph's, this TR6 I have only had for a month and i havent done the service yet! Just been enjoying it now the sun is out. I just read the old service manual and it says use an SAE 90 viscosity GL4 in both axle and transmission. The more modern chemistries work at lower more concentrated treat rates and are a lot more "active" unless carefully formulated. There are products that can deliver both GL4 and GL5, but they are few and far between unless you wish to pay for chemistry you really dont need. I can understand the GL4 spec for the axle given the type of spiral bevel gear, the loading and the fluid change intervals are so low. . Key is servicing regularly (says the man who hasnt done it yet!). Something like Millers Oil Classic Gear Oil EP 80w90 GL4 looks about right. Castrol Classic EP 90. These are both GL4. I guess if i were going to hammer the final drive/axle I would go for a GL5 SAE 90 and go for the extra protection. But i would not put the GL5 in the gear box. The viscosity grade will be important. Dont go lower unless you are sure you know what you're doing.

[DavidBee]

Thanks ! When I re-read my post, it sounded a bit negative ("refreshingly"). My apologies to all and sundry Forum blighters, not my intention at all. I find that posts tend to be technical and that's a refreshing surprise, especially after my long lapse, due to pressures at work.

[Ralph Whitaker]

Finally got around to draining my gearbox and overdrive of the Millers AG90 and re filling with Millers Golden Film SAE 40.  I have to say second gear is now easier to engage and the overdrive is more positive in action.

I wonder why engine oil is specified for the TR3/3a and  Hypoy for the TR4., unless it was discovered that it gave better protection.

Overdrive Services in Sheffield always reccomend straight 40, and I have always thought that EP oils should not be used in a gearbox as it hampers the syncro rings from doing their job.

Ralph