What Gear Oil should I buy?
 

I have been running Redline sythetic 75/90w. Is the Mobile 1 syn power good? The local parts store that carried Redline went out of buisness. I could drive into Seattle to buy some if it is better. What weight are you guys running? I want to change the front and rear diffs. and the transfercase this weekend.

Thank you,
Willie

Mobil 1 is good, redline is better. Royal Purple makes good gear oil too. How many miles do you have on the Redline? It should be good for 90,000 miles.

I have 100,000 miles on it. I should have changed it a long time ago.

Willie

I just filled mine up with Mobil One.

80W 90 Lucas, you can see the difference. I ran mobile on in the front and lucas in the rear to test, the rear oil is MILES better over 1 year. I now use all lucas in all three diffs

I have seen references to using the heavier 75w140? as well, do you use it in all the tc , diff, and swivel balls joints or limit it?

Lucas better than mobil 1, that's funny. Lucas is the bastard stepchild of the lubricants family though their synthetic gear oil is OK. Also Mobile is a city in alabama.

I have 75w140 Rotella gear oil in all 3 gear boxes. You can feel the sluggishness in the winter though and I'm sure gas mileage suffers a bit also. Once I'm sure my transfer case is all sealed up I will switch back to Redline in the proper factory recommended weight.

I would agree for engine oil, but for gear oil lucas has never let me down, and resists breakdown better than others in my experience. Lucas climbs the gears better than anything I have ever seen.

Read this and you can pick your own oil!

i use lucas synthetic it works great and quiets the gears a little

I personally don't think it matters which one you choose. They all work ok in my book. Even with regular gear lube, you can get way more miles out of an axle assembly if you change it often enough, which most people don't. My chevy truck has 246k miles on the original rear end with regular lube and it's not falling apart. Just choose a brand of Synthetic that you can get consistantly so you don't end up mixing. Change it often enough ..and that depends on driving conditions as well as age/miles. Mobil 1 seems expensive from what I've seen, Royal Purple is hard to get ..and last time I got a price it was kinda high. Valvoline Synthetic is one good choice B/C you can get it at just about any NAPA and price is reasonable. I have used it vehicles for years. Couple yrs ago I since switched over to Walmart fully synthetic cause it's 1/2 price. Seems to work just fine. I can't remember who supplies it, but they told me at the time.. (subject to change too)..

Is one brand 5% ..maybe 10% better than the other? Who knows.. maybe, but probably not. Does it really matter on my Disco that already has 135k mi? Almost for sure, "NO". I think you will be fine with any choice of the products you listed.

Can i replace my gear oil on a disco 1 with 80w 90 conventional or does it have to be synthetic? Thx.

You can, but most recommend synthetic.

Conventional is fine, it's all I've ever used in Rover diffs for 40 years. Make sure to check the level on schedule and change it on schedule (or more frequently if you off-road in water) and you'll be fine.

I would suggest 85w140 however.

Any gear oil, as long as (GL5), is better than running it too long without change,
If you can't change it often enough, synthetic will last better In long change intervals.

OK great thank you so much.

By the way do i need any limited slip differential additive. I'm planning on doing both differentials and the transfer case. Thanks. :)

No.
The Land Rover limited slip diff that used clutches was discontinued in the 60's, and wouldn't fit the Disco half shafts anyway.

Oh OK great that save me a buck. by the way I bought the 85w 140 gear oil and drained and started filling the transfer case with it. It seems very thick. I live in south Florida where its in the high 80s most of the year. I know you recommend it but would it be OK to use for the transfer case and both the front and rear differentials? Thanks. It's a 1999 disco 1 by the way

I use 85w140 wherever gear oil is called for.

After doing my homework on gear oils for many different rigs (motorhomes, half ton Fords, Rovers)....I came up with the conclusion that dino 85-140w is a very popular weight to run in most gear oil applications. That's what I use.

OK after hearing all the good things about the 85w 140, I filled up the transfer case with it and it shifts like butter lol. However I wanted to go with something closer to what the manual recommends for the differentials so I choose the 80w 90 for the front and rear differentials.

Was this a good choice? Thanks :)

Your fine. I just believe in the KISS method. I would have used the same oil for all 3 diffs...But at least you serviced them, time to move on to the next project!

Nothing wrong with that, though I use the same 85w140 in transfer case and diffs (have for 40 years in Rovers) and never had any issues.
I buy it in 5 gal pails and have a pump on the pail to pump it in.

Oh nice thats the way to do it. Thanks for your help and advice to all of you on this forum. I wouldn't have been able to do this service without you guys. Thanks.

What Gear Oil should I buy?

The cheapest synthetic that meets the spec, I use Fuchs 75/90 for general road going use but if offroading a lot you could use thicker 80/140, it makes little difference especially to performance or noise.

Hi, can I use 85/140 Synth, in a 2007 LR3 for the dif oil change out? TY

What does your owners manual say ?