Club 80-90 Forums

I was told by the local motor factor that any 80w90 gearbox oil was suitable for the Syncro, however on closer inspection of what they had it was GL5 80W90. So I left it.

He couldn't explain the difference between GL5 and GL4 - though insisted they were all the same.

I take it i made the right decision by not buying it?.

Interesetingly, I then went to GSF - and they just had Morris 80w90 and couldn't tell me if it's GL4 or 5. So I didn't buy that.

Anyone know if the GSF oil is ok?

cheers,
Rich

2 theories on this..
Dont use the GL5 stuff as it will disolve the "white metal" bearings/bushes in the box...
In reality, this is only a problem if the oil gets hotter than approx 100 degC (going on what some american guys have done with Unimog 404 gearboxes)
If a syncro box can heat the oil up that far... then it possibly is a problem..

The other theory is that as long as there is good oil in there, it will be ok..
I have run Comma SX semi synth GL5 gear oil in my 2wd 5 speed for 7 years.. the thing has done loads of miles (100k) at high speed.. sure it leaks a little, but thats coz as far as I can tell its done 200k miles+..

IIRC Harryman has the same oil in his syncro...

My current (borrowed) box has Redline MT90....

I've got some of the following ordered. Looks like it could be just the thing.

http://www.difflock.com/cgi-bin/wm10/wm ... item=DF457

The oil in a syncro box on a hot day(yes even in the Uk) can exeed
100 gegrees on a long run.

Cheers Russel

Just need to see if we can actually de bunk this "corrosion" problem.. maybe it was early gear oils that caused the problems..

IIRC Harryman has the same oil in his syncro...

he does, and for the cost the Comma SX semi-synth seems the easy answer, might as well take no chances with a GL-5.

Can't help with the debunking,but imagine it would take a long time to dissolve, but have heard the odd gorror story on US forums about white metal/bronze in oil(whether exagerrated or true)

Er Clive.. Comma SX semi syth IS GL5.........

BUt I think that semi-synth GL-5s don't need th additives that dino GL-5s need to reach that spec - my understanding anyway

But I think that semi-synth GL-5s don't need the same (corrosive) additives that dino GL-5s need to reach that spec - my understanding anyway

I think it's worth saying that if you are in a spot, and can only get GL-5 for a while, we're pretty sure it won't do any harm in the short term, till you can drain and change it - is that about right?

Prob. better than running oil full of metal, be it bronze or steel, and definitely better than running a low oil level

according to Comma website their semi synth gear oil is available in both GL4 & 5 --Redline MT90 makes a big difference-I found--for the £50 odd it cost to fill the gearbox it stopped the crunching 2nd gear & made the changes far smoother--didnt make the gearbox last any longer tho--

it stopped the crunching 2nd gear & made the changes far smoother--didnt make the gearbox last any longer tho--

you mean it didn't stop it failing eventually! I agree its good stuff (I could only get MTL), but suppose if it was damaged already then no oil could stop that eventuality.

Yeah, but just changing to Comma SX made a huge difference to my 2wd box.. that was 7 years ago and its done at least 100k hard miles since.... (+ an extra oil change change)

Has anyone tried out the stuff that I've ordered from the DiffLock shop?

Classic GL4 Gear Oil 80W90


I don't want to put it in my spanking recon'd box if it's the wrong stuff.