Technical Gearbox Oil: GL4 or GL5?

[astio]

Anyone knows a bit more about gearbox oil?
The manual says: TUTELA ZC 75 SYNTH that's SAE 75W-80, API GL 5

I understand that GL5 might harm the synchromesh as it is usualy bronze and GL5 is no good for "yellow metals".
Is this a real problem on punto's gearbox?
I'm talking about a 1.2lt, 16v, 80HP mk2 punto's gearbox witch I think (please corect me if I'm wrong) it is a synchronised gearbox.

Is there a different aloy (other than bronze) for punto's synchro so there is no problem at all or is there a chance that mama FIAT might not have paid atention on this (I don't believe that)?

Anyway the question is: GL5 and no problem or GL4 for "safety" ?

 

[astio]

Anyone?

 

[LandieMan]

I know that in the Land Rover community, we tend to stick with GL4, which is BW very cheap at Wilkos!

An admin on the forum I belong too said that he soaked a scrap diff and gearbox in 2 different tests (2 diffs and 2 gearbox components), in GL4 and GL5 over 6 months and there wasn't much in it.

I can't find the experiment, however here is a thread on it.

http://www.series2club.co.uk/forum/forum/index.php/topic,53850.0.html

Of course there will be variances with a modern Punto, but metal hasn't changed much. (Except Steel).

 

[Peter Pick-Up]

www.castrol.co.uk "which oil for my car"