Thread: Whats the preferred oil in the LT95 Gearbox and Transfer

Originally Posted by fcnutter

Hi all,
Not sure on exact oil to use in my Perentie LT95 gearbox and transfer case.
Would appreciate advice on correct factory specs for this set up.

Cheers, Adrian

I had asked the same question a couple of months ago, see this thread

http://www.aulro.com/afvb/military-l...-perentie.html

Good old engine oil. I use the same as what I run the V8 in my 101 - 20W 50. DON'T use gear oil - that will **** it quickly...

There are many discussions on this subject already. Have a browse through the military vehicle sections.
I use engine oil in all my LT95's.

This was my experience: Castrol Super RX vs VMX-80 in LT95. Real world report.

Cooking oil

When the LT95 was designed, oil companies had not yet developed GL5 manual transmission fluids, and for a low viscosity lubricant the choice/compromise was engine oil.

GL5 manual transmission fluid has been available for many years now and has far superior high pressure, and other characteristics, as required for light vehicle gearboxes, compared to engine oil.

GL5 manual transmission fluid is suitable for the LT95 gearbox, and it should not be confused with 'gear oil' which is not suitable.

If you don't care, stick with engine oil, if you want something better, use a GL5 lubricant.

Edit: BTW, as spudboy observed, the viscosity of GL5 is lower than engine oil. This is the case at ambient temperature, but the viscosity index of GL5 is better. The important result is that when the lubricant is at the normal operating temperature, much higher than ambient, the viscosity of the engine oil will be lower than the GL5. That is an important quality for a gearbox lubricant.

Originally Posted by Bush65

When the LT95 was designed, oil companies had not yet developed GL5 manual transmission fluids, and for a low viscosity lubricant the choice/compromise was engine oil.

GL5 manual transmission fluid has been available for many years now and has far superior high pressure, and other characteristics, as required for light vehicle gearboxes, compared to engine oil.

GL5 manual transmission fluid is suitable for the LT95 gearbox, and it should not be confused with 'gear oil' which is not suitable.

If you don't care, stick with engine oil, if you want something better, use a GL5 lubricant.

Edit: BTW, as spudboy observed, the viscosity of GL5 is lower than engine oil. This is the case at ambient temperature, but the viscosity index of GL5 is better. The important result is that when the lubricant is at the normal operating temperature, much higher than ambient, the viscosity of the engine oil will be lower than the GL5. That is an important quality for a gearbox lubricant.

Due to the lt95 using white and yellow metal bearings, you should not use a gear oil. High temps cause the additives to break down dissolving the white/yellow metals. Modern engine oils have friction modifiers and detergents, causing difficult gearchanges. I have spent hours with the Penrite tech dept and the best oil we have come up with is HPR30, as it doent have friction modifiers. I have tried this in a couple of boxes including mine, and it has cured the gearcgange problems.

Originally Posted by landrover dave

Due to the lt95 using white and yellow metal bearings, you should not use a gear oil. High temps cause the additives to break down dissolving the white/yellow metals. Modern engine oils have friction modifiers and detergents, causing difficult gearchanges. I have spent hours with the Penrite tech dept and the best oil we have come up with is HPR30, as it doent have friction modifiers. I have tried this in a couple of boxes including mine, and it has cured the gearcgange problems.

Are we getting our 'gear oils' and manual transmission fluids mixed up?
GL5 is EP hypoid rated and may attack copper/bronze. OK in a diff but not a gearbox. I agree with Bush65 regarding use of manual transmission fluids but not sure about the GL5 reference - possibly he meant GL4...