So one of the first things I did to my land rover when I got it is the 60k service.

I used 85w140 in the diffs and transfer. About two weeks into it I started to develop a roar and 50mph and 70mph plus. It's been kicking me in the rear what it could be. So yesterday I decided to switch out the transfer case to 80w90 just like what the manual says. Roar is completely gone I am so relieved my tc does have 103k miles.

So if this happens to you might want to swtvh back to 80w90. In the diffs the 140 seems to be doing ok but I'll prolly switch back to 80w90 on those too

Just my 2 cents an experience with 140 weight

 

What kind of oil did you use? Full synthetic?

 

Lucas for the 140. this time for the 80w90 used supertech dino cause I dont want to sink too much money into a trial. I'm switching it to amsoil ep 75w90 though later

 

I run mobil1 75w90. Have had it in both diffs for over a year and no problems, just put it in my T-Case and it leaks now, didn't before.

 

it leaks because the oil is slightly too light for the seals that were designed.

 

I rather it leak a bit than roaring

 

Thats what I figured, next time around I'm not going to use the Mobil1, the only reason I used it was because my dad had a case he never used and I'm a broke college student.

 

I too have developed a roar since adding the thicker oil. Mine is at take off and it goes away at around 30mph. Comes back if I gun it while at speed. On a positive note the shift clunk I used to get when slowing down then hitting the gas has
gone away. Perhaps a happy medium?

As this oil was suggested by Disco Mike I would love to hear him chime in on this.

Have been suspecting I need to switch back to the lighter oil however keep the BG additives.

 

Well my saying to this is not one vehicle is the same, some will be fine with 140w some wont...I def was not. Roaring in a transfer case is the last thing you want..that piece of equipment is bucko bucks and who really wants to break down a transfer case..not me.

I think what it is..my land rover was never ever ever taken offroad before me, so it didnt get "as much" wear. I'll be putting some AMSOIL 75W90 EP in the transfer case, and cheapie 80w90 in the diffs, since those i change out after a big off road trip anyways....just my .2 cents

I will put an argument out on this though, if our transfer cases are specced for 90 weight oil, maybe just maybe some (me) experience the roar since some parts might not get enough lubrication. because when its cold, the transfer case did not make any noise with 85w140, but once warmed up it sure did. I've opened the transfer case panel and found no bad gears or wear marks that would alarm me that my t/c is bad, but as soon as i switched to the right specced weight...booom butta smooth

 

Exactly what happened to me and at highway cruising at about 65+ intermittely roared as well...so this caused me to replace the u joints thinking that it was that, balance wheels and getting super worried...and all it was is the freaking wrong weight of gear lube