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GT6 diff/gearbox oil specs and recommended brand(s)


richhl
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EP90 for both. You need GL4 spec - NOT GL5 and I'd be wary of anything that claims it's both GL4 and GL5 combined. You'll probably have limited choice in your local Autosupplies these days, unless you buy via mail order. I ran a gearbox day in my garage last year (next one is coming up!) and had a devil of a time finding GL4 locally, eventually having to order about a gallon of the stuff from a central supplier. I'll use more of it this year again, given that some of the club cars had almost empty diffs and gearboxes and so a litre wouldn't have lasted very long.

As with engine oil, go by price - a suspiciously low price will give you some idea of what the oil will be like. The two branded versions I have in the cupboard are Granville and Motaquip, all that I could find locally.

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The factory spec was actually EP75 for a fill from dry, with EP90 being the top-up spec. So 80 or 80/90 should both be OK. Some people recommend 140 for diffs because of the higher average road speeds and thus higher diff temperatures these days.

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11 hours ago, Colin Lindsay said:

Why do they call it 80/90? Surely it can't be both...  so why don't they call it 85?

 

11 hours ago, johny said:

think its like engine oils (eg 20/50) as its got the viscosity of an 80 when cold and a 90 when hot rather than having the temperature/viscosity curve of a monograde..... 

Johny has it spot on. We use multigrades for a very good reason in engines, and really should in gearboxes and diffs. They are often forgotten, and just because better stuff was not available at the time of manufacture does not mean we should ignore progress in oil manufacture.

Gearbox stiff and notchy on a cold day until it warms up a bit? That is likely as not the oil is too thick. Use a thinner cold grade oil, so lower first number and use an original spec (or there abouts) second number and you have the best of both worlds. 

There is also available a gear oil that is an 85-140, so the correct sort of initial number, but maintains viscosity so in theory may work well. Moss sell it as a "noise reducer" for slightly worn components. I have some to try in my Toledo where the axle has a slight whine, but as it is the CWP it would be a massive expenditure to correct (needs new CWP) but hoping the new oil may help. Otherwise the axle is in fine fettle, doesn't even leak at all. Shame it is most noticeable at motorway cruising speed....

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all Rootes used engine oils in gearbox and OD , the laycock spec is engine oil but the Triumph gearboxes and tooth profile  were not good enough and needed the ep90  so an exception was made to use 90 in the OD aswell ( well you cant seperate them )

as for using GL5 in harsh environments i can vouch that when renault changed our oil supplier and made GL5 in the bulk tanks  without consulting our  engineers the following year we had some reliable  commer/ dodge diffs suddenly started to eat thrust washers we had used for donkeys years without problems   it  cost a fortune on warranty.   

pete

death was quite quick.

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3 hours ago, Badwolf said:

So much for modern 'liquid engineering'.

That phrase should refer solely to beer, and only certain brands at that.

(In fact beer is much the same as engine oil; some brands are excellent, others not so good, and some are indistinguishable from 20/50 in both taste and smell.)

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12 minutes ago, Colin Lindsay said:

That phrase should refer solely to beer, and only certain brands at that.

Colin, please - I think you're referring to liquid art.

Liquid engineering is keg stuff, surely? Which, as (I hope) we all know, is monotonously mediocre and definitely isn't real beer!

Cheers, Richard

PS: Oh, and would you kindly stop using the "B" word. "Brands" are created by marketing people with their focus groups and budgets. Great beer is created by skilled artisans, and delivered to your glass by gifted publicans.

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31 minutes ago, Badwolf said:

Colin - Do you want me to post you some of my home brewed beer. A bit of a cross between 99 octane and hypoid.

Wouldn't it soak through the envelope?

12 minutes ago, rlubikey said:

Colin, please - I think you're referring to liquid art.

Liquid engineering is keg stuff, surely? Which, as (I hope) we all know, is monotonously mediocre and definitely isn't real beer!

Cheers, Richard

PS: Oh, and would you kindly stop using the "B" word. "Brands" are created by marketing people with their focus groups and budgets. Great beer is created by skilled artisans, and delivered to your glass by gifted publicans.

Oh Lord, please don't let them start on beer the same way they do with coffee. Baristas, cofficionados, they're all spotty teenagers with two hours training in how to fill a cup.

I'll not offend the real ale enthusiasts other than to say: it's not to my taste. Yet.

Currently: Mythos has my vote, with Hophouse13 and Mourne Mist a close second.

mythos-beer.jpg.3dca79d5024b63925ff9ad7552e3a4cd.jpg

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5 minutes ago, Colin Lindsay said:

Wouldn't it soak through the envelope?

Oh Lord, please don't let them start on beer the same way they do with coffee. Baristas, cofficionados, they're all spotty teenagers with two hours training in how to fill a cup.

I'll not offend the real ale enthusiasts other than to say: it's not to my taste. Yet.

Currently: Mythos has my vote, with Hophouse13 and Mourne Mist a close second.

mythos-beer.jpg.3dca79d5024b63925ff9ad7552e3a4cd.jpg

Shouldn't that be a blue colour?

Dave

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What happened to the fill tube that used to be supplied with gear oil - clipped on under the cap?? Last time I bought some (20years ago at least..) these were standard!! Does anyone sell bottles with this anymore?

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Used some comma gear oil recently, and the tube pulled out from the cap (so it goes inside the bottle)

However, I have found them just too tricky for filling diffs, so resorted to the slow and thumb-aching process of using an oil squirt can (noxxle cut off, length of tube attached, so I can sit behind the car and fill. Also lets me know how much oil is lost as it only takes 250ml, so how many times does it need refilling...)

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