The Triumph Dolomite Club - Discussion Forum

Hi all.what oil should go in an overdrive geatybox and does the go in the back axle. Myles.

Dollyby 2 wrote:Hi all.what oil should go in an overdrive geatybox and does the go in the back axle. Myles.

Hi

EP80W-90 for both.

Paul

Yes but the overdrive box needs GL4 spec not the later GL5. Either can go into the diff but the overdrive wont like the additives in the GL5 oil hence the earlier spec GL4 is used

Tony

Thanks Paul. Tony.excuse my ignorance but is that mineral oil? Myles.

It will be mineral based but there will be a lot to choose from no doubt. As long as it says GL4 its good for the gearbox and diff and GL5 for diff only.

Tony

There is a lot of ignorance on this subject.

There was a time when EP additives as used in EP90 for diffs were not kind to graphite based sintered bronze
components. The graphite would leach out and make the oil black. Ive seen quite a few boxes in my time where this has
happened.

GL4 is the earlier spec which doesn't have the EP additive. Moss and co used to recommend ST90 for Sprint and other
boxes for this reason.

Modern GL5 EP oils do not have the same effect on the sintered bronze, so buy a good brand like Castrol and all will be well.

In the case of a late Sprint box with very few sintered bronze bits I wouldnt be so inclined to worry anyway. Early ones
have bronze mainshaft bushes.

In the smaller boxes its the laygear thrust thrust washers that seemed to deteriorate most.

Jonners

Thanks Tony.Jon.very helpful as always.

Do not use any GL5 oil, the additives in this do not like 'yellow' metal and eat it away. The best oil I have found is Morris lubricants 75/80.

GL4 is readily available. EP80/90 whether it's GL4 or GL5 is an EP (extreme pressure) oil so makes no difference really. My local Halfords had clearance on Castrol GL4 so I stocked up at £3 a litre!

I'm all for debate on various subjects but its kinda irritating when some of us have extensively researched this and
yet we get over posted by those who either havent read earlier posts on the same thread with contrary advice....
or just have to have a say for whatever reason.

"yellow metal" would be what exactly Ken? Bronze, brass, copper, gold, sintered or solid.

And exactly what chemical change is "eating"...?

Sorry but your obvious engineering talents call for some better science here.

Do gearboxes need an EP additive anyway? Do any of you posters actually know this? Where did you look to find out.
"EP" was designed for the hypoid bevel gear trains in differentials....lots of sulphur
in its early formulations...so lots of leaching of graphite in sintered bits.

The EP additives in modern oils do not do this...so anything bought in the last 5 years should be ok. The Sprint box was originally
rated for a 75 weight oil, so 80W castrol manual is ok and is what I use in my Sprint boxes and have done for a good while.


Jonners

The sulphur dissolves the thrust washers and or synchro's. Diffs need ep.
Gearboxes need no ep and use gl4. A gl5/ep is too strong and the synchromesh rings have trouble to cut the oil film from the cones of the gears.
A gearbox does run fine with even a motoroil 10w40.

Jeroen

Jon Tilson wrote:... we get over posted by those who ... havent read earlier posts on the same thread ... Jonners

Anyone who's read these threads will have seen that some questions are asked over and over again. Perhaps it would help to avoid this if the Dolomite-related section were subdivided into general topics, such as Electrical, Engine, Transmission, Chassis, Steering, Lubricants, etc, as people might then be more likely to search for an answer before posting a question?

Quite simply , I posted the information from the dolomite sprint operation manual and it states Gl4 so why put anything other than this in

Indeed so Jeroen....

MGB/cambridge boxes and all the transverse stuff runs quite happily on engine oil.

SD1 LT77 boxes started life on 75 weight and then moved to ATF.

I've often wondered about running a Sprint box on ATF...

Jonners