trans oil

[Lawrie]

Has any any one had or seen damage of the :yellow metal: parts in the transmission when using GL 5 oils instead of the GL4 oil
I just had a look at the transmission in our 33 after it had done about 45000 miles on GL 5 85/140 oil.
Not a mark or wear on either the synco rings or thrust washers, all within secs and working good.It is a very nice trans
As 85/140 GL 4 oil here is not availible ,I have used the GL5 85/140.
Lawrie

[42merc]

I also use GL5 in my early Ford transmission & rear end. I have monitored the trans for wear of the yellow metals and after 30K plus miles, cannot see any appreciable new wear or the brass dissolving into the oil.
I compare the flap about GL4 - GL5 to the No Lead hysteria of days gone by.
Plus it has been printed before that the gear lube producers say GL5 will not harm yellow metals.
Let the fun begin.

[JSeery]

More recent manufactures of GL5 claim it is safe for yellow metal. However some other sites have claimed transmission damage with it (non-Ford later model cars/trucks) and some vehicle manufactures state they will void your warranty if you use GL5. That coupled with Fords original recommendation to use Mild Extreme Pressure has always lead me to go with the GL4. I don't view it as a "flap", just information some might be interested in. If you are happy with GL5 don't see any reason to knock it, I just tend to lean toward the cautious side when it is fairly easy to get GL4 and GL5 is not really needed.

[aussie merc]

i went to a full synthetic [syntrans 75/90] cold shift much improved and no inication that theres any wear again you use what works for you

[Talkwrench]

What brand of oil Lawrie?

Seems the only one we have here is Penrite mild EP. GL4 the tech said too me it sits just under a 140.

[Lawrie]

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Rob, I tried castrol stuff GL 4 made for lite duty manuals ,80/90,BUT it was way thinner than the usual 85/140 that I use in the rear axle,so I.m back using the 85/140 that I have used for years.
Lawrie

[Talkwrench]

So its Castrol stuff hey.. Axle EPX 85 -140?

[dumb person]

The way it was explained to me, by an long time flathead owner, is there is additives, including sulphur in some and not in other oils.
He'd seen some gearboxes black inside from sulphur.
I can't remember if it was the GL4 or GL5 that had sulphur in it.

At any rate, the erosion he was seeing was one molecular layer of highly reactive yellow metal at a time being stripped away each time the gears were shifted, or in the case of a model T, thrust washers make a rotation.
If left stationary, they'd take up to 500 years to dissolve.

Not first hand info', make use of it if you want. Basically says driving will wear it out faster.

[JSeery]

Originally Posted by dumb person

The way it was explained to me, by an long time flathead owner, is there is additives, including sulphur in some and not in other oils.
He'd seen some gearboxes black inside from sulphur.
I can't remember if it was the GL4 or GL5 that had sulphur in it.

At any rate, the erosion he was seeing was one molecular layer of highly reactive yellow metal at a time being stripped away each time the gears were shifted, or in the case of a model T, thrust washers make a rotation.
If left stationary, they'd take up to 500 years to dissolve.

Not first hand info', make use of it if you want. Basically says driving will wear it out faster.

They both do, it is a matter of the amount.

"Most lubricants for manual gearboxes and differentials are hypoid gear oils. These contain extreme pressure (EP) additives and antiwear additives to cope with the sliding action of hypoid bevel gears.

EP additives which contain phosphorous/sulfurous compounds are corrosive to yellow metals such as the copper and/or brass used in bushings and synchronizers; the GL1 class of gear oils does not contain any EP additives and thus finds use in applications which contain parts made of yellow metals.

GL-5 is not necessarily backward-compatible in synchro-mesh transmissions which are designed for a GL-4 oil: GL-5 has a lower coefficient of friction due to the higher concentration of EP additives over GL-4, and thus synchros can not engage as effectively. Also, transmissions which explicitly call for GL-4 oil may have been designed around this lower concentration of EP additives and thus may contain yellow metal parts which GL-5 will corrode."


"API GL-4. Oils for various conditions - light to heavy. They contain up to 4.0% effective anti-scuffing additives. Designed for bevel and hypoid gears which have small displacement of axes, the gearboxes of trucks, and axle units. These oils are standard for synchronized gearboxes, especially in Europe, and may also be recommended for non-synchronized gearboxes of US trucks, tractors and buses and for main and other gears of all vehicles. GL-4 oils may also be used in many limited-slip differentials.

API GL-5. Oils for severe conditions. They contain up to 6.5% effective anti-scuffing additives. The general application of oils in this class are for hypoid gears having significant displacement of axes, generally non limited-slip differentials. They are recommended as universal oils to all other units of mechanical transmission (except synchronized gearboxes specifying GL-4). Some GL-5 oils in this class, which have special approval of vehicle manufacturers, can be used in synchronized manual gearboxes. API GL-5 oils can be used in limited slip differentials only if they correspond to the requirements of specification MIL-L-2105D or ZF TE-ML-05. In this case the designation of class will be another, for example API GL-5+ or API GL-5 LS."


This is somewhat beating a dead horse here. If you know and understand what the different GL rating are and want to use the GL5 gear lubes in your transmission, do it. Worse case would be a rebuild sometime in the future, it is not going to be a catastrophic failure. Brass and copper material is removed one atomic layer at a time and it requires a lot of heat and pressure to happen as well. It is a long term process. Also, some suppliers of gear lubes claim they have changed their products so that it is no longer a problem. To me, GL5 is not required with pre-hypoid gears and/or in transmissions, so why use it? Ford recommended Mild EP gear lubricant for their transmissions and in todays terms that is GL4.

[Lawrie]

I use it as there is not a GL4 availible here that is the right vicosity.see my post 6
Lawrie

[russcc]

I use Lubriplate SPO-227, GL 140. Lubriplate always has quality lubricants. Not sure if is GL 4 or 5. I will ask, and post their response.

[JSeery]

Originally Posted by russcc

I use Lubriplate SPO-227, GL 140. Lubriplate always has quality lubricants. Not sure if is GL 4 or 5. I will ask, and post their response.

Is that SPO-277?

[Phil Gillespie]

Morris Classic Gear Oil Specs.pdf


I go with Morris Oil. Classic Gear Oil AG 140. Gearbox and diff. Happy with their oils.
Phil NZ

[doghair3]

Do you use the Lubriplate in the rear differential as well?

[Anteek29]

I am running Sta-Lube GL4 single weight 140 in my '41 tranny and diffy.