Consequences of wrong grade gearbox oil?

[Fr0dders]

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.

 

[Jonny69]

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.

 

[Simon]

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.

90 is thicker than the 85 recommended so it wont be a durability issue

 

[Jonny69]

I think you missed the point of my post

 

[Simon]

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 ?

 

[Dogbreath]

So now I'm definitely confused. Is it GL-4 or GL-5?!?

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...

 

[Jonnycoupe]

Which bit? The bit that 25 > 8 so that means the GL is more important as the difference is greater?? ?

All of it?

Mainly the sarcasm.

Good post Jonny

 

[Fr0dders]

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]

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.

 

[Dogbreath]

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.

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.

 

[Dave L]

Same here, you're worrying about nothing.