I used motul Xcess 5-40w. Everything I changed the oil it came out golden/brown.

10-40w is more suited to high powered turbocharged vehicles. Try another full synthetic oil that is 5-30w

Did you use the same oil filter on both occasions?

I used Castrol VMX80 in my gb plus Nulon treatment. It was good for about 8000km when I noticed it was getting harder to shift and slight grinding in 3rd.
Changed to valvoline Duragear Gl4 synthetic. Been a happy camper since.

Ask any reputable tuner. They all go Synthetic.