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75-W90 Gearbox oil to GL-4 from Comma

Posted: 28 Apr 2011, 21:46
by silverbullet
After being told in no uncertain terms by my friendly LMF that transmissions requiring GL-4 oil can be safely run with GL-5 (he was wrong by the way) :
"It's bollox, just a later spec" as the guv walked out the door to deal with another customer...
So I went down the road to CAF (as I will do from now on) and asked the same question. Out came the Comma catalogue and there it is, 75W90 Semi-synthetic gear oil to GL-4 "for older transmissions specifically requiring an oil to GL-4 specification" :D
I bought 4 litres for a shade under £25 all in.
Should improve the cold 1-2 shift no end over the 80W90 that I have used before and at this price I'll change it every year.

Re: 75-W90 Gearbox oil to GL-4 from Comma

Posted: 28 Apr 2011, 23:15
by toomanytoys
But I have been using Comma SX 75w90 in the velle for last 11 years and 200k km.. its been fine... 2 changes... (GL4/5)
I'm also running Fuchs Syngear 75w90 in the Syncro (GL4/5) as there tech department said it was fine..

GL5 only oil seems to have the nasty addatives.. GL4/5 generally seems to not, from what information I gathered...

Re: 75-W90 Gearbox oil to GL-4 from Comma

Posted: 29 Apr 2011, 00:03
by Red Westie
toomanytoys wrote:GL5 only oil seems to have the nasty additives.. GL4/5 generally seems to not, from what information I gathered...

Well technically they both have 'the nasty additives' it's just that original GL5 spec oils have much more of them.
GL5 spec was designed for EP (extreme pressure) hypoid gears. This type of application requires additional shear strength so MORE of these sulphur based additives were used.

The actual problem is rare and only occurs at high temperatures as a chemical reaction between the sulphur based additives and yellow metal components such as brass/copper and phosphur bronze.

Early GL5 products were only tested to meet GL5 specs as it was thought they met and exceeded GL4 specs, Nobody thought of actually putting them through the GL4 testing regime until reports started filtering through about yellow metal damage.
My take on this....and I have spoken to several manufacturers help desks, is that it is only advisable to use GL4 spec OR GL4/GL5 oils, as these have been tested to meet both requirements and presumably have been formulated to meet the GL5 spec with alternative additives (this is my assumption and not fact I'm afraid, nobody was able to give me a definitive answer on this one)
And
Changing the oil for even the wrong stuff (GL5) is better than not changing it at all.....(of course,don't.. but you get my drift)

Martin

Re: 75-W90 Gearbox oil to GL-4 from Comma

Posted: 29 Apr 2011, 00:18
by toomanytoys
There is a manufacturer that specificaly states its GL4/5 oil is made for protecting the "yellow metals", but I could never get any... :roll:

Aidan spoke with Millers (and also Fuchs IIRC) tech departments some time ago and they both said the oils was recomended...

I have trawlled many technical papers over the last 10 years, many manufacturers listed the pec as GL4 mineral and for severe duty use their GL4/5 semi/full synth products...

The box from the velle will be stripped down this year.. and we will see what it looks like after 200k km of the SX75w90 in it.. ( its slightly tired @350k km on it.. but works very well with no noises, bu the 2nd gear "cold baulk" and its the original box as far as I can tell.. ive owned it since 150k km...)

Re: 75-W90 Gearbox oil to GL-4 from Comma

Posted: 29 Apr 2011, 00:25
by Red Westie
Well like I say....this scenario, as far as I can tell, is pretty rare and under extreme conditions (needs lots of heat)
I will definately be interested in seeing if there has been any 'noticeably' excessive yellow metal damage. I believe Aidan has seen the type of damage caused by this phenomenon so he knows what to look for over and above 'normal' wear and tear.

Martin

Re: 75-W90 Gearbox oil to GL-4 from Comma

Posted: 29 Apr 2011, 05:20
by Aidan
bronze coloured oil with brass and moly dust in it and very worn synchro rings

Re: 75-W90 Gearbox oil to GL-4 from Comma

Posted: 29 Apr 2011, 09:15
by silverbullet
Well this stuff is easily available, so don't get fobbed off by your LMF who should know better. My (now ex-) motor factors are all old enough to know but are clearly past caring and the youths there are learning nothing of course...very disappointing.

Moral: If you don't ask, you don't get.

Re: 75-W90 Gearbox oil to GL-4 from Comma

Posted: 02 May 2011, 23:02
by HarryMann
Good input Martin, Ian, Aidan et al, thanks...

Seems to have confirmed what was thought but maybe not known for sure 8)

Re: 75-W90 Gearbox oil to GL-4 from Comma

Posted: 03 May 2011, 06:46
by CovKid
Easily available as I've said before, Wilkinsons stock it - the only gearbox oil they do and its under £3 a litre :rofl

Re: 75-W90 Gearbox oil to GL-4 from Comma

Posted: 03 May 2011, 08:31
by silverbullet
Cold shift 1-2 still a bit slow/heavy but a lot better (when compared to a 2WD DG velle with an indicated 160k, just sold) and the "warm up" time needed to get a slick shift is definitely reduced, maybe only a mile or two.
Winter will tell what it's really like; I must change the rear onion and get some fresh boots on it, there's far too much play there which can't be helping at all.

Re: 75-W90 Gearbox oil to GL-4 from Comma

Posted: 09 May 2011, 14:41
by silverbullet
Definitely improved shift now the 80W90 lurking in the sychro hubs and R/G housing has been flushed out and diluted in the new runny stuff. Loads better but possibly slightly noiser in 1st/2nd?
Might be my imagination of course :mrgreen:

Re: 75-W90 Gearbox oil to GL-4 from Comma

Posted: 09 May 2011, 15:16
by crazydiamond
Ive just put Comma 80w90 GL4 in my Aircooled box and it feels really nice. In fact its an easier gear change than befor with its 15+ year old unknown oil!!! ho hum.

Re: 75-W90 Gearbox oil to GL-4 from Comma

Posted: 10 May 2011, 08:43
by silverbullet
crazydiamond wrote:Ive just put Comma 80w90 GL4 in my Aircooled box and it feels really nice. In fact its an easier gear change than befor with its 15+ year old unknown oil!!! ho hum.
I've got 21 litres of that, fresh and unused in a barrel!

Re: 75-W90 Gearbox oil to GL-4 from Comma

Posted: 10 May 2011, 23:35
by HarryMann
Ive just put Comma 80w90 GL4 in my Aircooled box and it feels really nice.

Geoff, it's best to wash your hands afterwards.. :D

Re: 75-W90 Gearbox oil to GL-4 from Comma

Posted: 01 Oct 2011, 17:23
by xpress
hi all. good thread. getting heavy gear changes and a bit of a rear whine from one to two, even with engine off. I was going to put ep 90 in it or would you suggest a thinner or multi viscousity oil?