Consequences of wrong grade gearbox oil?

  • Thread starter Thread starter Guest
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in which case they're telling fibs

I'be demanding either:

A) they drain and re-fill the box with an oil of your choice
B) a signed waiver that any fault deemed to be caused by the wrong gearbox oil from a suitably nonindependent inspection of your choice is their liability and they will pick up any costs incurred.
 
I don't think your gearbox is going to last long. 75w-90 is 5 numbers thicker than 75w-85, that's nearly 6% thicker than the manufacturer recommended. They recommend these things for a reason you know. My concern would be the GL-4 to GL-5 difference. That's 1 number on 4, which is a 25% difference, which is quite a lot. I think it's going to be very very different oil or they wouldn't have made the numbers so far apart.

Probably.
 
Jonny69 said:
I don't think your gearbox is going to last long. 75w-90 is 5 numbers thicker than 75w-85, that's nearly 6% thicker than the manufacturer recommended. They recommend these things for a reason you know. My concern would be the GL-4 to GL-5 difference. That's 1 number on 4, which is a 25% difference, which is quite a lot. I think it's going to be very very different oil or they wouldn't have made the numbers so far apart.

Probably.
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90 is thicker than the 85 recommended so it wont be a durability issue
 
Which bit? The bit that 25 > 8 so that means the GL is more important as the difference is greater??

Infact I wouldn't even be bothered about the difference in visc, more the 50% extra sulphur EP additives in a GL-5 oil. Hows that for a number ? ;)
 
frakker said:
So now I'm definitely confused. Is it GL-4 or GL-5?!?
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It's a GL-5 oil that meets GL-4 specifications I suspect. Not all GL-5 oils will cause an issue with copper, it would be better to contact Carlube and ask them about compatibility before potentially making a fool of yourself in front of the garage...
 
lol

guess it comes down to what will make you rest easier.

If you're not 100 % confident just buy some oil you will feel confident with and get them to change it for free and thank them for their understanding.

If that re-assurance from carlube is enough, then leave it in.
 
Jonny69 said:
Sensible post alert: I'd leave it. I've been using modern gear oils in ancient boxes and axles (that shouldn't use EP gear oil) for years and none of them have come to any harm.
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I'd be quite happy to leave it in as well; if the manufacturer says it's compatible then you can't get much more assurance than that.
 
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