Gen4 replacing diff oil

You are right I'm sure but if gl4/5 spec oils are suitable for use in a Jimny gearbox, not diff, why do Suzuki specify a gl4, and i have direct experience of this, why does it become increasingly difficult once at operating temperature to select gears in a Jimny box with gl4/5 oil in it?

GL4 / 5 combined specification oil can be used in GL4 applications, that's what it's designed for. It's been in my gearbox for the last few years without any issues. I don't know what spec was in before I did the service, but I can't say I have noticed any change in the gearbox shift.
I get the feeling reading online that Suzuki box shift can be a bit "notchy", hence some recommend Redline MT90 as the must have oil over other makes of GL4.. So not sure if the make of oil can make a difference if you have a "notchy" box, but luckily it's not an issue I have on mine.

Again I ask the question why would I have significant issues with selecting gears when using a gl4/5 that immediately resolved itself as soon as I replaced it with a straight gl4?

Hi Lambert,
I don't know and don't doubt for one second it made things better. I am just interested in trying to understand why it makes such a difference in your circumstances and did not in mine.
That said I don't know if my gearbox is smooth, it's just the same as it was before I did the oil change, I have nothing to compare it to. First gear can be slow to select if the vehicle is moving, the others select fine at any speed. However I class it as a gear box that is better changed slow rather than fast, rush it and it can fight back. Is that the difference? How did yours feel on GL4 / 5?

On paper it should not make any difference, oil is oil, it all comes out of the ground. What differs is the filtering (Synthetic/Semi etc) and the manufacture's additives, viscosity aside. I am due another service of the transmission in 4500 miles, so if GL4 is going to make a difference I can easily go this route, but don't want the expense of Redline MT90.

Mike

On mine the change is always precise and smooth, not like an open gate Ferrari but really nice and able to supply the correct gear however quickly you're able to go for it be that pootling with mother round the farm or giving it some beans on a track day. With the gl4/5 it was reasonable when cold but as it got up to temperature it would be virtually impossible to get down to 4th then 3rd and going up from 2nd was like trying to stir liquorice.

It doesn't seem to have done any lasting damage and wasn't in the box for more than 4 or so months a good few years ago but the difference going back to a gl4 was very marked.

Interesting, as you say that quite a marked difference.
Don't suppose you can remember the make of the GL4 / 5 you used?
I may give GL4 a go at the next oil change and see if it changes the characteristics of my gearbox. As I said, I have nothing to compare the current GL4 / 5 oil in my box as I did not know the oil spec it replaced. It could have been like for like, hence no difference.
Always worth a try, everything to gain, nothing to loose.
Mike