Thread: LT95 oil

It's easy.

Off the shelf Penrite have a full synthetic GL-4 75w-85 gear oil.

Use it.

The end.

Originally Posted by Red90

Actual 85 gear oil is the same a 30 engine oil. 40 engine oil would be like a 90 gear oil. Each number is a big change.

The range overlaps slightly, IIRC Syntrans 75w-85 is around 12-13cSt@100° so close to the bottom end of an SAE40'engine oil but yes, generally a 90 gear oil is equivalent to an SAE40

85 is 11 to 13.5
90 is 13.5 to 18.5

30 is 9.3 to 12.5
40 is 12.5 to 16.3

To add a wrinkle to this I'd been using rego search on Penrite site and it came up as 3500 Rover- which lists Tans oil for manual recommended. But on closer read it was 3500 Rover car. So different gearbox. When i put in 77 Range Rover it comes up with HPR 30 for manual transmission which is 20w-60. With "No substitutes" listed. Castrol recommend 15w-50 or - GTX 20-50 which is whats in it. So both Castrol and Penrite list engine oil in fairly high numbers for LT95.

When I put in 77 Range Rover it comes up with HPR 30 for manual transmission which is 20w-60

I put this in my 77 once and I couldn't change gear once the transmission got hot. This was about 20 years ago so they may have changed the formulation since then, but 20w 50 was the one which worked well cold or hot.
Regards PhilipA
BTW my 1981 in Saudi had gear oil in it when I bought it and the thrust washers in the transfer were completely gone as they were in a mate's 77 Four door ( conversion) car . I can remember shooting all the material out of the intermediate shaft with compressed air . Of course his shaft and bearings and gears were also shot.

G'day All,

Yes oils ain't oils. Castrol GTX 20w50 ZDDP levels have changed over the past 30 Years. When your vehicle was made the API rating of GTX was SJ/CE and the ZDDP package was approx. 1400PPM. Then GTX API rating was SM/CF and ZDDP package was approx. 800PPM.
The current GTX 20w50 API rating is SN and I cannot find what ZDDP level it has?.
I suspect your problem is associated with lower ZDDP levels in the current GTX20w50 you are using.

I had a similar shifting problem with our Leyland mini clubman that used GTX 20w50 for engine and gearbox/diff. Low ZDDP levels in the oil was the problem. Changed oil to Penrite Classic Mini 20w50 API SJ/CE with 1390PPM of ZDDP. Within 100 Km the gearbox was shifting perfectly and clutch was fully disengaging properly because the primary gear was free on the crank. A pleasure to drive now.

Do a google search for "ZDDP levels in oil" to get up to speed on why the ZDDP has been reduced for modern engine oils and problems with flat tappets on camshafts.
You can buy ZDDP additive to add to your GTX. "Redline Oil" has a ZDDP additive and a data sheet that lists how much to add to oil to reach a certain ZDDP level.

(On my Series 11a I use Castrol Syntrans, a GL4 oil for the G/B and Transfer because of a Rocky Mountain O/D fitted.)

Google search GL5 oils and Bronze components. It's not corrosion its erosion due to tearing, as the additives in the GL5 form a hard protective coating on the softer bronze and under load tears up the softer bronze.

How this helps.
Chris

I have never seen 50wt oil listed for the LT95 in official handbooks - 40wt max. Just use 15w40 mineral and all will be good - dont make things harder than it needs to be.

Garry

Ordered some Penrite 15w-40 with zinc HDdp additive. Will give it a go.
Thanks all