IMO, skipping all the details, I would give the ASX 75W90 Synthetic a try. It sounds ideal for the diff, and the lower cold weight may allow easier shifting.

Most of the descriptions seem oriented towards heavy-duty vehicles.

I agree that their information looks quite overlapping, confusing, and not particularly applicable to a sports car such as the FD.

Dave

 

yes that it seems fine for the dif.
also i am thinking Gx for the trans following dave advise for the gl4 oils for the transmisions althought shell recomends the Ax.

thanks for your time.

 

Although the GL4 may seem more suitable for the trans, the lower weight (75W90 vs 80/90) and the fact that the ASX 75W90 is synthetic, may make shifting easier with less grinding and notchiness with the ASX 75W90 than with the GX, which is apparently not synthetic.

As I said, though, you may have to experiment with more than one trans lube to get the best cold shifting performance.

Good luck!

Dave