Land Rover and Range Rover Forum banner
1 - 3 of 3 Posts

·
100 quids for a days work son..
Joined
·
240 Posts
Discussion Starter · #1 ·
did some experimenting on some gearbox fluids, put the Redline MTL90 2 quarts and Redline 75-90 gear oil both in synthetic form. And wow the results are awesome. The gearbox leak has lessen to tiny drips and the 5speed works GREAT with minimal noise. Just want to share it to ya all. Just an alternative to ATF which felt waaay too thin for the gearbox.. also running 5-30 motoroil after a motor flush and WOOOW this Rover feels sweet ! that's all Happy Holidays ya all ...
 

·
Premium Member
Joined
·
3,208 Posts
I was left with the same impression after switching from Mobil One ATF and 75-90 gear oil to the Red Line MTL and gear oil in my LT77 and LT230. I've subsequently put the Red Line gear oil in the diffs and swivels. The price is comparable for the gear oil but the deal on Mobil One at Costco makes it hard to step up to Red Line for the engine, especially when you change oil every 3K miles.
 

·
Registered
1995 NAS Discovery -3.9L14CUX Manual Trans
Joined
·
11 Posts
This is an old thread but the title is great :)

Red Line Oil is expensive but wow, you can actually call their California phone number and talk directly to their tech team about your application! Worth the price, imo.
So.. that's what I did.

I am looking for the latest (mid-late 2024) recommendations for gear oils for our 1995 (NAS spec) Land Rover Discovery (aka: Disco 1) with the R380 manual 5-speed transmission [all info included for the search engine]. I called Red Line and got the following advice:

Recommendations:
  • R380 Manual transmission:
    • MTL 75w80 GL-4 [primary recommendation]
    • MT-85 75w85 GL-4 [got a noisy old trans? If it doesn't get too cold in your neck of the woods, try this]
    • MT-90 75w90 GL-4 [got a noisier older trans? If you are below the Mason-Dixon Line, try this]
  • LT230 Transfer case
    • 75w90 GL-5 Gear Oil [primary recommendation]
    • 75w140 GL-5 Gear Oil [got a noisy old diff? Give this one a go]
    • Heavy Shockproof Gear Oil [got a noisier old diff? Want maximum Diff protection? go for this one]
      • Low fluid friction like 75w90 but film thickness greater than 75w250
  • Diffs: [same as the transfer case]
    • 75w90 GL-5 Gear Oil [primary recommendation]
    • 75w140 GL-5 Gear Oil [got a noisy old diff? Give this one a go]
    • Heavy Shockproof Gear Oil [got a noisier old diff? Want maximum Diff protection? go for this one]
      • Low fluid friction like 75w90 but film thickness greater than 75w250

Note: GL-4 basically means there are no friction modifiers. This is necessary for the synchronizers to function properly; synchros actually need some friction.. if they the oil is too "slippery" then they don't work well. Additionally, friction modifiers are generally made of chemicals that are very corrosive to brass and bronze (pretty much every synchro on the planet is made of one or the other).


Bottom Line:

For my 1995 NAS Disco1 stick, I am going with MT-90 for the tranny and Heavy Shockproof for the transfer case and the diffs.

If your experience/opinion differs from all this, please reply and let us know!
 
1 - 3 of 3 Posts
Top