[NiBe]

Hi,

I was doing this "differential clunk fix":
https://www.e90post.com/forums/showthread.php?t=175885

btw it really works the clunk is gone. When I was removing propeller flange from differential some oil (max 50-100ml which is 10% of diff capacity - 1L) leaked out. The vehicle was probably not 100% leveled.

In the diff there is this oil:
Castrol Syntrax Universal Plus 75W-90 which has API/GL5 specification

Unfortunately I don't have it but I have:
Castrol Syntrans Transaxle 75W-90 which has API/GL4 specification

After some reading GL5 means that it is for diff (extreme load with shocks) and GL4 is for transmission (not that extreme load). The main difference should be more additives in GL5 which provides the extra protection but these additives can be harmful in transmission so that's why GL4 is used in transmissions.

So I'm thinking:
1) do nothing
2) top up 100ml of Castrol Syntrans Transaxle (GL4) to the diff
3) buy 1 L of Castrol Syntrax (GL5) and use 100ml of it to top up the diff

And my question is: do you think that 2) is OK solution? Or even 1)?

I know that the best solution for the car is 3) but it is not exactly economical solution. So I decided to ask first before spending 20 USD on oil which will be 90% unused. It is 2007 E91.

Thanks