LT95 oil

**Busted Syncro** · 10th October 2020, 08:20 PM

G'day All,

Another downside with GL5 Sulpfur based EP packages is it causes modern Nitrile oil seal to harden up and eventually leak. When these early vehicles were manufactured most were fitted with Neoprene oil seals (some with Viton) and safe to use with Sulpfur EP packages.
(Google chemical resistance of Nitrile, Neoprene and Viton.)

Difficult to get neoprene seals now so I have been fitting Viton oil seals to the Series 2a 1966. Unfortunately they are 5 times more expensive however, last 5 time longer and are better at handling excessive heat.

To use Viton seals you need to measure the housing and shaft diameters and thickness of the seal being replaced. The bearing shop will do the rest.

Another reason to look at modern Sulphur free EP GL5's and some GL4 oils.

Chris

**Meccles** · 10th October 2020, 08:36 PM

Both Castrol and Penrite techs only recommended a GL4 oil in 75-90 range as having right viscosity and sympathetic to soft metals in gearbox. Both did not recommend a GL5 oil. Thats good enough for me if i end up replacing engine oil in the gearbox.

**asmit** · 21st April 2021, 01:49 PM

Here's great read for anyone interested:
https://www.widman.biz/uploads/Transaxle_oil.pdf
Page 4 of that article analyses manufacturers specifying engine oil in gearboxes.

I'm running this 75w90 GL-4 in the gearbox and tcase... seems to shift quite well hot or cold.
GEAR OIL 75W/90 GL-4 | Hi-Tec Oils

**Homestar** · 21st April 2021, 02:09 PM

Originally Posted by asmit

Here's great read for anyone interested:
https://www.widman.biz/uploads/Transaxle_oil.pdf
Page 4 of that article analyses manufacturers specifying engine oil in gearboxes.

I'm running this 75w90 GL-4 in the gearbox and tcase... seems to shift quite well hot or cold.
GEAR OIL 75W/90 GL-4 | Hi-Tec Oils

Probably ok up your way but I think that would be too thick during a Melbourne Winter. OEM always specced engine oil for the LT95 so I'll keep using that. I have a drum 75/90 GL4 for the diffs and hubs I use but the engine and gearbox all get the same oil.

**rick130** · 21st April 2021, 05:25 PM

Originally Posted by Homestar

Probably ok up your way but I think that would be too thick during a Melbourne Winter. OEM always specced engine oil for the LT95 so I'll keep using that. I have a drum 75/90 GL4 for the diffs and hubs I use but the engine and gearbox all get the same oil.

A 75w-90 manual trans fluid is the same viscosity as a 15w-40 engine oil right through the temp range, their kinematic viscosities are almost identical.

**Homestar** · 22nd April 2021, 07:54 AM

Thanks for the clarification.

**101RRS** · 22nd April 2021, 11:22 AM

Good engine oil is usually cheaper than good gearbox oil so why change from what works.

**rick130** · 22nd April 2021, 11:43 AM

Because a good manual trans fluid has the right friction modifiers for decent synchro function, engine oils have the wrong curve, their coefficient of friction decreases with decreasing differential rotational speeds.

**101RRS** · 22nd April 2021, 01:08 PM

Maybe but engine oil works and has always works and keeps on keeping on and I often hear of failures when the LT95 is changed to gear oil. Just not worth it.

**barney** · 22nd April 2021, 02:12 PM

I was told that the LT95 has a plastic square drive on the oil circulating pump that will quite likely chew out if you use anything that is thicker than the oil specified in the workshop manual (engine oil - 20W-50), when i was getting my gearbox repaired a few years back.
Previously, a northern beaches land rover "expert" (not Ayers) refilled my LT95 with 80W90, this was the same day he snapped the brake adjusted on the rear brakes and didn't tell me. I found out as I was trying to stop at a set of lights just down the hill. He refused to fix it, as in his words "it was old and ready to snap".
Expert? my arse!

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