Differential Oil (GL4)

[SGOUDREAU]

I have a Triumph TR6 and must use GL4 oil in the differential. My Question: is GEAR OIL the same as DIFFERENTIAL OIL?
Pennzoil Platinum Gear 75W90 GL4 could be considered I suppose but then they have another product that they call AXEL OIL (GL5). There seems to be a difference between GEAR OIL and AXLE OIL. What do you think? Could GEAR OIL be used safely in a differential?

Thanks

 

[Dyusik]

GL4 would be your manual tranny choices. Every time MT90 is recommended in threads like these, and for a good reason.

 

[expat]

Diffs typically have hypoid cut gears, often requiring special extream pressure additives.

It has been stated that the angle of the gear teeth cut in the crownwheel and pinion on Triumphs (like yours and mine) are of such an angle that many feel an MT oil (like MT90) would be acceptable.

Having said that, I doubt that there is any advantage in using MTL's either.

Although GL4 is often stated as a requirment due to some yellow metal components in the diff, many GL5 lubes now have sufficent buffers to perform perfectly satisfactorily in our diffs.

 

[dlundblad]

If you for sure need a GL4 in the rear diff because of yellow metals, I would stick with that. Redline MT90 works and there's also Sta Lube GL-4 80w-90. Since your up North, I am not sure on your availability though. 1 fluid for the transmission and diff is convenient.

So in short yes, gear oil (MT90 for example) can safely be used in a diff. I've always called diff oil "gear oil" though and a manual transmission's fluid "MTF".

 

[nyumski]

i think as long as manual says it needs GL4 it means that even ur differential has the same metal thing that gear use

 

[zeng]

Originally Posted By: expat
Diffs typically have hypoid cut gears, often requiring special extream pressure additives.

It has been stated that the angle of the gear teeth cut in the crownwheel and pinion on Triumphs (like yours and mine) are of such an angle that many feel an MT oil (like MT90) would be acceptable.

Having said that, I doubt that there is any advantage in using MTL's either.

Although GL4 is often stated as a requirment due to some yellow metal components in the diff, many GL5 lubes now have sufficent buffers to perform perfectly satisfactorily in our diffs.

+1
We're no longer in the 70s 80s era .....
move on, folks.

 

[wings&wheels]

Hi fellow 6'er, some of the newer syn GL5 lubes should be able to be used in GL4 apps, ask the manufacturer. I use Redline 75w-90 which Redline confirmed as yellow metal safe. Redline MT90 in the transmission. Let's see a pic. Here's mine..40k miles, one owner before me, no winters ever...yes the color is original.

 

[Rand]

Some GL-5 will be fine.
Since it calls for gl-4 I would use a 75w90 gl-4 which would be mostly gear oils
formulated for manual transmissions


Some Gl-5 gear oils are not safe.

if you want to learn more try googling
gear oil copper strip corrosion test

 

[ARCOgraphite]

Stunning 6er! I recall fondly test riding (with my father driving), a new Triumph Stag v8 down at a BL dealer in Lowell, Ma. We also test drove something REALLy special, but I have a cold with a fever 9 that I never get fever!) and I cant recall the Marque. Tube chassis, near square wheelbase x track with BL power!

 

[wings&wheels]

Thanks!

" Tube chassis, near square wheelbase x track with BL power!"...TVR?

Hope you feel better...too nice today in NH to be sick.

 

[Y_K]

Some gear oils are GL-4, GL-5 and MT-1 at the same time.

 

[SGOUDREAU]

Originally Posted By: wings&wheels
Hi fellow 6'er, some of the newer syn GL5 lubes should be able to be used in GL4 apps, ask the manufacturer. I use Redline 75w-90 which Redline confirmed as yellow metal safe. Redline MT90 in the transmission. Let's see a pic. Here's mine..40k miles, one owner before me, no winters ever...yes the color is original.





Hi,

Very nice TR6! I'll try to figure out a way to post a photo of my TR6 (76 Java Green)

Thanks for the replies

 

[supercity]

Originally Posted By: SGOUDREAU
I have a Triumph TR6 and must use GL4 oil in the differential. My Question: is GEAR OIL the same as DIFFERENTIAL OIL?
Pennzoil Platinum Gear 75W90 GL4 could be considered I suppose but then they have another product that they call AXEL OIL (GL5). There seems to be a difference between GEAR OIL and AXLE OIL. What do you think? Could GEAR OIL be used safely in a differential?

Thanks


Pure semantics - differentials contain gears so you could call the lube oil either. Automotive differentials do typically contain Hypoid gear sets so are sometimes referred to as Hypoid gear oils which will be GL-5. Tractor diffs usually contain only bevel gears which can be satisfied by GL-4 performance or even lower.

There are many ways to blend an oil to meet GL-4. There are engine oils that qualify for GL-4. There are also GL-5 hypoid oils that qualify for GL-4. The performance and copper compatibility of various GL-4s can be vastly different in the real world.

 

[SGOUDREAU]

Originally Posted By: wings&wheels
Hi fellow 6'er, some of the newer syn GL5 lubes should be able to be used in GL4 apps, ask the manufacturer. I use Redline 75w-90 which Redline confirmed as yellow metal safe. Redline MT90 in the transmission. Let's see a pic. Here's mine..40k miles, one owner before me, no winters ever...yes the color is original.





Trying to post my TR6 picture here:

 

[wings&wheels]

Beautiful, stock example of the late TR6. I always thought the simple raising of bumper height w/ smaller signals now below the bumper was a very elegant solution to the bumper height regs. Nice redlines...my car is as original as I can keep it, with the exception of the tires. Redline tires look awful against magenta...I have period correct tires, but they are blackwalls.

Enjoy your car.

 

[tdi-rick]

Just my $0.02 worth.

Land Rover diffs are spiral bevel, not hypoid (excepting the 8HA Salisbury, which is metric version of the Dana 60 with Land Rover cheddar cheese axles, but I digress...) so technically only need a GL4.
They are specified as requiring a GL5.

For diffs I wouldn't use a GL4, and as previously mentioned, most GL5's with a sulfur/phos additive package are buffered, particularly those blended for transaxle usage if we are worried about copper corrosion numbers.
Or you could use a GL5 diff fluid that uses a borate additive package instead of sulfur/phos. Think some of Texaco's diff oils. Here in Australia Penrite offer one.

 

[supercity]

I was going to mention Caltex's RPM Borate but it's not all that practical.

 

[Y_K]

Chevron Delo ESI gear oil in USA is one of those