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GT6 Diff oil


Alex Lowe
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2 hours ago, alan.gilbert_6384 said:

Ah, what's the difference with this one Ive been using apart from the E at the end, the data sheet says it should be fine but I would appreciate some advice, thanks.

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If not clearly stated as suitable for manual transmissions, do not use. The synchros will not grip enough, and will lead to crunchy changes. Nothing to do with yellow metals...

(the yellow metal is more of an issue in diffs where heat comes into play, but most GL5 oil is yellow metal safe if you check with the manufacturer.)

 

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  • 2 weeks later...

Hi All,

Thanks very much for all the suggestions.  I really value your empirical knowledge.  Still trying to get the bottom of the GL4 or GL5 for the gear box.  Here's what I've got so far.

1. Triumph spitfire 1500 hand book, GL5 (overseas, ?)

2. Haynes manual; Hypoid gear oil, viscosity SAE 90 EP.

3. Spitfire 1500 work shop manual; Hypoid 90, with GL4 for overseas, this is opposite to the hand book above?(maybe brexit was a thing then as well ;).

4. Herald 1200 12/50 vitesse 6 chart; Hypoy gear oil (what's the heck is hypoy).

 

Aghhhhhhhh

P.S. I'm doing this because the weather is rubbish :( and I can't go outside.

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accepting some modern GL5 is yellow metal friendly my experience of having oil specs changed without forthought caused diff thrusts to degrade within warranty and whilst truck diffs have a hard life all down to purchasing going for a GL5 when GL4 was the spec and not realised till crates of diffs started to arrive 

Hypoy is just a name suitable for hypoid gear sets , which has additives to suit the   hypoid  diff  longer tooth profile than  a bevel gear pretty much all shown as EP extreme pressure oils 

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You have my bit from above. Not sure why Triumph erronously state GL5 in a handbook, when even current cars are clear GL5 is unsuitable for manual transmission.

I read somewhere many engine oils would meet GL4 spec, pretty sure it was on a spiel that was posted a while ago on oils.

If you wish to try GL5 oil, go ahead. It may be fine. But do report back after a few hundred miles and let us know if the synchros are working OK.

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many makes  with better gearboxes used  engine  oil in  gearboxes  (and OD)  but the small chassis triumph boxes  has some very weak points like the dreaded mainshaft tip spigot and layshaft needles which is why 

ep90  is specitfied  ,(also was agreed by laycock)  yes there are modern oils that may be better these days  but if you want any life from these weedy gearboxes  i reckon  stick with EP 

Pete

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2 hours ago, thescrapman said:

Engine oil can be used successfully in overdrives and gearboxes, I am pretty sure that is what MGB use.

not in the diff though

Apparently most engine oils meet GL3 or 4 spec! Lots of TR owners seem to like it, and laycock spec'd it for overdrives. But as always, manufacturer instructions trump all else, and Triumph spec'd a number of gear oils.

I have been thinking about oils, not too much as lots of stuff happening in my poor brain at present. But I wonder how many people baulked at the idea of using 20/50 oil in the 60's, and insisted it was the spawn of satan, instead using straight 30 oil. (I know somebody who has used straight 30 oil in their mk3 spit for over 100K now). 

I guess that argument is why so many are concerned about anything with the work "synthetic" on the tin, when in fact oils have been using synthetic additives for decades. 

I REALLY like commas SX 75-90 GL4 gear oil. Doesn't smell ghastly even after a few years use. May start using it in my Triumph box, when I run out of my current stock of gear oil.

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3 hours ago, Pete Lewis said:

many makes  with better gearboxes used  engine  oil in  gearboxes

Including Triumph! At least, the constantly changing oil specification for late TR7s (with the Rover gearbox) went through a brief period of being engine oil.

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  • 2 weeks later...
On 08/07/2020 at 10:53, clive said:

Apparently most engine oils meet GL3 or 4 spec! Lots of TR owners seem to like it, and laycock spec'd it for overdrives. But as always, manufacturer instructions trump all else, and Triumph spec'd a number of gear oils.

I have been thinking about oils, not too much as lots of stuff happening in my poor brain at present. But I wonder how many people baulked at the idea of using 20/50 oil in the 60's, and insisted it was the spawn of satan, instead using straight 30 oil. (I know somebody who has used straight 30 oil in their mk3 spit for over 100K now). 

I guess that argument is why so many are concerned about anything with the work "synthetic" on the tin, when in fact oils have been using synthetic additives for decades. 

I REALLY like commas SX 75-90 GL4 gear oil. Doesn't smell ghastly even after a few years use. May start using it in my Triumph box, when I run out of my current stock of gear oil.

Hi All, 

Found this really interesting article on the oils, goes someway to exapliaing why oil companies say GL5 is safe for yellow metals, but it also explains why its no good for synchros, worth a read.

https://www.widman.biz/uploads/Transaxle_oil.pdf

@ Clive like your suggestion of Commas SX 75-90 GL4 gear oil, just found this on fleabay and its on its way ;)

https://www.widman.biz/uploads/Transaxle_oil.pdf

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for,t last 10-12 years or so, been running a fully synth 80-140 oil

in gb, od, diff,  ne downsides at all,

no stiff changes, slow sycro action, 

boxes been apart often,{ broken teeth / snapped shaft / bent shaft. } syncros fine, thrusts fine, od comes in muchess faster, even in 1st

nee yella stuff on oil changes, 3 times a year some times, 2 mostly depends on hoo long been at W1+ for long periods,

{ 250+  degs  is an oil killer, hence changes }

And, it meks things a wee bit quieter too.

 

Befoer I used this stuff, I bunged in some ATF in GB OD t,give it a clean oot,

gear change was v v notchy, an GB was v v noisy

 

drained it oot after  aboot 300 miles, an bunged in the 140 stuff,

niva looked back since

 

As for the Commas SX 75-90 GL4 gear oil,

total sheite, honestly,

it goes black an pours like thin pish after a 500  mile thrash 200 miles at W1+

feels like pish too, nee lube quality left, like most  of the others did which I tried.

 

but, if yer a potterer,  no building heat up, then it,ll be ok

M

 

 

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Penrite Pro Gear oil 80/140,  not the ordinary stuff as its diff, so  P Tech said.

git it of Dave Parker at classic group,

think its 15-20 £ for 2.5 litres,

muchess cheaper if got at the shows.

an muchess cheaper than owt on Flea Bay

07391 590149

https://penriteoil.com.au/products/pro-gear-80w-140-full-syn

ev a read thru all the blurb

 

 

M

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Thank you, Marcus.

I've had a read and Penrite say their extreme pressure additive is 'generally safe for yellow and white metals'. That's good enough for me and I will give it a go in the GT6.

I've already put a mineral EP80W140 in the Salisbury axle on my Scimitar GTE, replacing the specified EP90. The diff is a lot quieter, with less chatter than before and so far no adverse effects. One of the guys on the Scimitar forum has been using it in the axle of his SE5A racer for years and recommends the thicker oil. I'm already thinking about putting this Penrite synthetic in the Scimitar - it must be better than the mineral oil even if it is nearly twice the price!

Nigel

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