Manual Gearbox Oil Question.

[sierra]

2.5CRD manual 6,500km with a noise lifting the clutch in neutral when warmed up. It mostly goes away when the clutch is right out, called 'Oh that's gearbox rollover mate, they all do that to some degree, bring it in hot and we'll have a listen'.
Just in case it was low oil level that didn't get checked on the 1,500km I took the level plug out and the level was perfect but the stuff dribbling out was less than impressive. Like warm dirty piss with a similar consistancy.
Decided to change it myself as the easier option and found almost 5L of Castrol EPX 80W/90 manual gearbox oil GL5, must have had it for 10 years.
The owners manual calls for 75W/90 hypoid GL4 as the closest brew to the Castrol.
It's in, lovely and thick compared with the crap that was in there and it shifts fine, perhaps a bit tighter on 2nd and selecting reverse. I haven't driven it to get it hot enough to check for the rollover noise but it's good to know it's got some decent oil in there.
Bottom line is, does anyone think it will cause problems, not so much the 80W instead of 75W but the GL5 instead of GL4 or GL3?


Right, GL5 contains higher sulpher levels for extreme pressure protection but is corrosive to brass and copper which may be present in the syncro rings? I'll ring Castrol on Monday and change it straight away if they say it's incompatible for that or any other reason.

[mff64]

Right, GL5 contains higher sulpher levels for extreme pressure protection but is corrosive to brass and copper which may be present in the syncro rings? I'll ring Castrol on Monday and change it straight away if they say it's incompatible for that or any other reason.

It will be interesting to here what the Castrol bloke has to say. I asked a question some years back(Castrol bloke) at a field day and was told 'do not put a gl-5 oil in a gearbox because the friction modifiers in a gl-5 oil are different in that there is a lot more pressure created between the crownwheel and pinion'. If you put a gl-5 in a tranny the modifiers will not work as there is not the same pressure created and the modifiers will not work.
It sounds sort of right but what about the bearings in the diff, would they not require a gl-4 ........maybe he got mixed up with the sulpher being hard on copper and brass

[sierra]

Thanks for the input.
Shows how confusing it is when that Castrol guy said that but the GL5 Castrol I used is marked as 'differential and manual transmission fluid' but it did say 'suitable for some manual transmissions'. After reading a fair bit last night I'm of the opinion that GL4 contains some sulphur but not enough to cause corrosion problems in the expected life of a gearbox containing copper and/or brass. GL5 has higher sulphur levels and is the superior extreme pressure lubricant because of that but will reduce the life of brass and copper syncro rings by about 50%
Anyway, it can stay in until Monday when I ring Castrol and I'm sure they will cover their arse by saying to change it and then it will get Penrite manual gear oil 80, 80w/85 GL4 suitable for 75w/90 GL4 spec and suitable for Mitsubishi (all models including 4WD but not Sigma or Starion which use Transaxle 80)

http://www.penriteoil.com.au/products/g ... ear_oil_80

You have to wonder what they put in there in the first place, although they specify the 75w/90 hypoid range it was certainly the consistency of auto trans fluid and totally gutless to feel, dirty too. I had a 93 Ford Courier 4x2 cab chassis 2.6 petrol for 9 years from 50,000km to about 150,000km. At 80,000km I checked the oil level before I changed it, must be when I bought the Castrol, the level was fine and the oil was spotless and felt good so I left it. I never looked at it again because there were no leaks and I bet it still looked good at 150,000km. The box was faultless.

[sierra]

Bought the Penrite Manual 80 80W/85 then rang Penrite for confirmation and they said wrong oil, it needs SIN Manual 75W/85!
Took it back and they didn't have the Sin Manual[$55?] and wouldn't refund the $24 for the poxy 2.5L of Manual 80.

I have to admit that although with the EPX 80W/90 hypoid GL5 it shifted alright, especially warm and was quiet, it was noisy cold in neutral with the clutch out. As loud as the engine! At 750rpm it was quiet????

To cut a long story short it got refilled with the Manual 80. The viscosity of all 3 oils is very close at 100C, 14.3, 12.2 and 12.5 but at 40C the castrol is a thick '139', the Manual 80 is '110' and the synthetic 75W/80 is only '77'
Pumping the man 80 into the gearbox I could feel how much easier it flowed compared to the Castrol and it didn't stink of additives but feels like oil unlike the slop that came out.
On the road it's quiet in neutral while cold, shifts beautifully and no sign of clutch rollover rumble, yet.