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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - GL-4 Hypoid Gear Oil - Diff

Where can I buy GL-4 85W90 or 140W hypoid gear oil that is safe for yellow metals in my TF diffs?

John Twist recommended Sta-Lube API/GL-4 Multi-Purpose Gear Oil SAE 85W90 for hypoid gears from NAPA. It's no longer available at NAPA. The CRC (maker) website says that it is discontinued.

Some brands are "GL-4+" or "GL-4/5". All gear oil that I find for hypoid gears is GL-5. I want GL-4.

Installing new axles in TF681 and need to be up-and-running in five days!

Thanks for your help,

Lonnie
TF681
TF7211



LM Cook

Lonnie:

I use Red Line MT-90. It's a GL-4. O'Reilly Auto Parts carries it. You can also order it from Amazon and Summit Racing among others. Price points range between $15 - $23 plus shipping for a quart. O'Reilly's prices it at $23.99.

Jim


Jim Rice

MT 90 is what I use also. Made a good difference in the shifting of the TD.
Bruce Cunha

I use Redline MT-90 in the gearbox in my TFs, but not in the diff. The Redline website states that it is not for hypoid gears.
https://www.redlineoil.com/mt-90-75w90-gl-4-gear-oil

Still looking for GL-4 hypoid gear oil for my diffs.

Lonnie
TF681
TF7211
LM Cook

Lonnie, you need an E.P.90 oil( extreme Pressure).Try Penrite, Gear Oil. Mild EP.
R E J Stewart

MT-90! Used it in the MGB and in the TF. No guessing. PJ
PJ Jennings

Lonnie:

Your correct. My error...I used the MT-90 in the gearbox. I used Sta-Lube API/GL-4 Multi-Purpose Gear Oil SAE 85W90 for the differential. As you noted, that's not available now. I checked several other sources and getting the same "no-stock" availability. That said, Moss carries SAE 90 GL4 Gear Oil by Dynolite for hypoid gears. Currently showing in stock. P/N: 225-306. $15.00 a quart.

Jim
Jim Rice

I use Redline and Royal Purple in all my diffs. They are both excellent oils and safe on yellow metals.
Steve Simmons

This regarding EP oils:

https://www.machinerylubrication.com/Read/28958/ep-additives-effects

Regards, Tom
tm peterson

Good article Tom. Ran across this one: https://rymax-lubricants.com/updates/the-differences-between-gl-4-and-gl-5
George
George Butz III

Sta lube do a straight 90 or 140 in gl4
William Revit

Where is the yellow metal in TD/TF diffs? Are the ball or roller "separators" in the pinion and carrier bearings made of yellow metal? Or are there yellow metal thrust washers behind the spider gears?
Bob
Bob Schapel

Good question, Bob -

I kinda remember reading that diffs have yellow metals. I have never been inside a diff, so I don't have a clue. The Service Parts List and the WSM don't mention brass or copper in the TD/TF diffs.

However, the Moss and Brown & Gammons sites show diff thrust washers that appear to be brass or copper.

I noticed in my recent research, that GL-5 gear oils vary in the corrosiveness of additives in the oils. The ASTM D130 Copper Corrosivity Test is used to identify the corrosiveness. The results range from 1A (least corrosive) to 4B (most corrosive). Some "internet experts" say that a rating of 1A or 2A is OK for diffs with yellow metal parts.

> GL-4 for gearboxes with brass synchros (1A)
< GL-5 for hypoid gears in diffs. Seems most GL-4 gear oils for hypoid gears are no longer available.

I'll keep searching and report my results.

Lonnie
TF681
TF7211
LM Cook

Lonnie: What about this stuff? Is says its safe for yellow metals.

https://penngrade1.com/products/gear-lubricants/penngrade-1-classic-gl-4-gear-oil-sae-80w-90/
Christopher Couper

Great research Lonnie. Yes, the Moss catalogue photo shows the thrust washers behind the sun-wheels look to be yellow metal. Presumably the smaller dished washers behind the planetary gears are also yellow (They are items 25 and 27 in the exploded diagram.) It might would be worth someone who has contacts at Moss, asking if Moss thrust washers are compatible with GL5. Also someone with original TD/TF diff parts could do some experiments with GL4 and GL5 oils in their garage/lab? GL5 would be superior if the thrust washers are not an issue.

The similar washers in MG midget / Sprite diffs are yellow. I have had many of them apart to convert them for use in TCs. (Very few have non-metallic fibre washers behind the sun-wheels.) I will ask the question about GL4 and GL5 oils on a Midget / Sprite thread on this site to see what they say. I will also start soaking some Midget / Sprite thrust washers in GL5 today!

The reason for my interest is that many years ago my late brother contacted a company to ask what diff oil was best for his TC racing car, fitted with a Midget / Sprite diff. The diff crown-wheel and pinion were toast after a couple of races. It was definitely an oil issue. We assumed that the advisor had recommended the wrong oil, so I have been a bit edgy ever since about diff oil. I have not bought gear oil since I became aware of the yellow metal issue many years ago but assume I have been using GL5. The only container I still have in my shed is marked GL5.
Bob


Bob Schapel

Just looked up the "Midget and Sprite Technical" archives on this site. Lots of different views but generally it seems they are not as concerned as we T-Typers. For several years I have heard lots of people mention the issue but have not yet heard of anyone actually having trouble by running GL5 in a TD/TF/Spridget diff. I will go and soak some spare Spridget thrust washers in GL5. I will try to find an old bearing with a bronze cage and add that to the mix.
Bob
Bob Schapel

Lonnie

90 or 140 here, take your pick--

https://www.ebay.com/str/performancepartsautosupply?_trksid=p4429486.m145687.l149086
William Revit

Bob-
-It'd take years for anything to happen, -if ever- It's the sulpher content in the oil that supposedly eats into the yellow metals, GL5 has more than GL4-

The only issue I've ever come accross using the wrong oil is when you put (some) GL5 oils into a gearbox-
The extra aditives in some GL5 oils live a film on the surface of syncro rings (steel or brass) and can reduce the effectiveness of the syncro rings---It only seems to effect cars that are toddled about, If you drive them normal/hard the rings stay clean and work ok

willy

William Revit

There are brass cupped thrust washers for the slider gears. They are no longer available. At least I haven’t found a source for them. These require a GL-4 spec. Hypoid gear oil. With the TD-TF I’ve been using the Dynolite oil from Moss for the diffs and MT90 on the transmissions.
W A Chasser

Help a newbie here. The TD shop manual seems to say that the same oil can be used for the gear box, steering box and rear axle. Is this not correct?
Chuck
CR Frakes

Penrite, an Australian company still make the correct GL4 oil.


B W Wood

CR, yes, 90 weight gear oil in all three.

Jud
J K Chapin

The yellow metal is the thrust washers for the spider gears. These cupped washers are NLA. If they fail your carrier will become junk.

I had to replace mine when I restored TD-4834 as DPO had been using the wrong oils. I bought four used carriers before I found a serviceable one.
W A Chasser

This thread was discussed between 10/07/2024 and 13/08/2024

MG TD TF 1500 index

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