EP Oil and 20/50 Engine oil mix for Gearbox

[cook1e]

The previous owner of my Dolomite told me he had filled the gearbox up with a 50/50 mix of EP Gearbox oil and 20/50 Engine Oil as he has been advised that this was best for Overdrive Gearboxes.

I certainbly didn't trust this mix as I'd rather go with what Triumph intended and have now drained the Gearbox/Overdrive and replaced with gearbox oil. I used EP80 as I undertsand that EP80 is best for refilling from empty and EP90 for top up of the overdrive box. If anything the gearbox is a bit quiter with the new oil and the overdrive certainly works the same so I'm happy with the decision to do this.

So a bity of a stupid question as I've already done it but does anyome else believe that a 50/50 mix of EP Oil and 20/50 Engine Oil is OK for a Triumph Overdrive Gearbox?

[garyf]

I've thought about doing this myself with my Vitesse Overdrive Box?

I have a mate who owns a Big Healey with an Overdrive Gearbox and I know he runs Engine Oil in that, not sure what grade but he reckons he gets better gear changes and its what was recommended by BMC?

I suppose TriumpH must have specified EP90 for a reason, some of the Small Chassis Triumphs don't have the strongest of gearboxes and EP Oil may not breakdown like Engine Oil?

(P.S. Have you tidyed that bench yet Cookie? ;))

[Hogie]

Mixing oils in general is not a clever idea as you do not know what effect the different constituents will have on each other.
On the TRiumph gearbox/Overdrive you can put almost anything in and it will work - not sure how good soapy water is though.

Gearboxes are interesting things. They have no Extreme  Pressure components yet some manufacturers (TRiumph in particular) recommend EP oils
Overdrives had a major warning in the 50's not to use EP oil due to comination of the clutch but TRiumph changed that as well.
Unbelievably gearbox oil works pretty well in gearboxes and makes O/D's perform 100%.
ATF works even better.

Thicker oil will quieten things down and possibly reduce the odd leak. However thicker oil in the O/D could produce too much pressure in the pump and or not drain away quickly causing the O/D clutch to drag.

At the end of the day put in what you are happy with but don;t mix them.

Roger

[thescrapman]

I know someone who runs his Spitfire OD box on 20/50. No mixing it with anything.

Seems to work OK.

[cook1e]

So it sounds like the previous owner may not have made a big mistake by using Engine Oil but a mix probably wasn't a good idea. I'm happy that I changed it for EP80 anyway :-)

I purchased a sort of Giant Syringe with a tube which made topping up a bit easier considering I didn't want to take the tunnel out or cut an access hatch in it. The Syringey thing also works for extracting oil so it should be good for getting the oil out of Triumph Diffs that have no drain plug :-)  

And No I haven't tidied by bench up yet !

[heraldcoupe]

All of the BMC gearboxes I've owned have been specified to use engine oil, as stated above it's what the manufacturers specified for the overdrives in our cars as well, irrespective of Standard Triumph's instructions,

Cheers,
Bill.

[GT6 M]

Ev a deek thru thru here. quite intresting article, ratched fre the depths of me comp.

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

M

[junkuser]

Thanks for posting that Marcus, an interesting read.

In the 1950s I worked on lots of English gear boxes, mainly Morris and Austin, when they used engine oil, usually just "SAE 30".

Almost all had surface damage on the straight cut gears.
Having no knowledge about oils, I used to put straight 90, gearbox oil in them (as used in early American Ford boxes) in the hope it would prevent recurrence of the problem.  
They synchromeshed OK, but I have no idea what happened in the long term.  Just no complaints from the owners.

Lots of well used English cars down here in those days.

[nang]

FWIW I once worked for a bus company that used ATF in the manual 'boxes in their Mercedes coaches. These coaches did literally millions of km's running night and day with no gearbox problems that I'm aware of.
Tony.

[Richard B]

Well ATF was recommended for the LT77 box as fitted to Ranfe-Rovers, Land-Rovers and TR7's.

[GT6 M]

Richard_B wrote:

Well ATF was recommended for the LT77 box as fitted to Ranfe-Rovers, Land-Rovers and TR7's.

Is  a Ranfe-Rover  a new model Rich,(think)(think)(whistle)

M

[Pete Lewis]

as the small chassis gearbox was a small upgrade from the standard eight with all its overloaded and unreliable features already built in you reduce the spec of the oil away from what Triumph specified at your expense when the layspindle and mainshaft spigot give up. or the teeth fatigue.
there is also the design of the tooth profile which comands an EP oil to survive.  stick to EP 80/90 GL4 and it might last as many years as it has already.
yes the base spec for the OD is engine oil , as used by many manufacturers, but its an approved fitment by Laycock  for triumph to use EP90
it will work fine ,, as it has for over 40 years.  

the gearbox and OD all use the same oil there is only one level filler  but two drain plugs   and no separation between the two parts.

pete

  

  

[Toledo Man]

Using anything other than gearbox oil alone will wreck the overdrive so mixing it with engine oil is a big no-no in my book. I know some gearboxes (the Acclaim is another example) use engine oil but that's what the manufacturers intended.

[Clive]

TM, it is the of manufacturers who specify the engine oil, and triumph overruled that and specced ep oil.
My opinion, for what it is worth, is that stick to ep 80 or 90 or even 80/90
There is even a synthetic ep 75/90 gl4 spec oil. That may be interesting, ford type 9 boxes also use gl4 oil and a very respected gearbox company recommend the 75/90

[Sheepy]

Richard_B wrote:

Well ATF was recommended for the LT77 box as fitted to Ranfe-Rovers, Land-Rovers and TR7's.

And the earlier classic range rover/FC 101/stage ones use engine oil in the boxes! (it was to do with the oil pump) gear oil was too thick.
My truck uses engine oil in the gear box also, as gear oil degrades the bronze rings in it.

I would use what triumph suggested in the day! but better to have some oil in there than no oil!
I would run It for a while then change it again?

When you drained it, was there any swarf or filings in the old oil?

[uksnatcher]

Any oil is good oil...short-term but what is in the oil is the main thing and what long-term damage will be done by adding the wrong spec oils.

ATF or synthetic low rated eng oil is thin oil so will find oil leaks...but what if its oil tight....... the oil has additives or lack of additives that will harm the soft metals in the O/D or balk rings/synchromesh systems so why alter the manufactures spec oils?

One example ....Peugeot spec expensive aluminium based gear oil for their gearboxes, people who knew better put cheap normal EP90 or ATF gear oil in and wrecked their gearbox....

Stick with what is tried and tested by somebody else with big pockets IE manufacturers, saves a lot of bother.

[GT6 M]

I always run ,or did run EP 90, now its gota be 80/90.

But last year I tried ATF, cos my syncros were giving a wee grate at 5k plus rev changes.
OK below tht, but a change nee matter whether it fast or slow, always gave a graunch.

Also was worried aboot the EP on the OD clutches.

Since useing the ATF,  I cannot beat the syncro change noo, no matter what revs,or hoo fast its changed gear.
there is no extra noise, and so far no leaks as such.

I looked at it this way,  If syncros were going, then what is there to loose if im going to strip box any hoo, will give it a try.
If there are probs later on, then I,ll change out box to spare I got alredy built up.

But so far, I cn only sy its alott better than it was.

ATF is aboot SAE 12 with one im use-ing, going by their tech  boffin
EP  oils are about 20-30 depending on grade.

BUT, deffo reccomend 85/140 in back axle.