Hi guys, i changed the fluid in my rx8 transmission, i used mobile 1 75w90 gl-5 fluid. I did this because the sources i checked said gl-4 or gl-5 was the grade of lube the trans needed. After i did this i start to get a grind in second gear at high rpm after the car is warm. I have about 800 miles on this fluid change and after some checking on this forum i read most members say gl-5 is bad for our transmission and gl-4 is what i should be using.

Could this mobile 1 fluid be messing my trans up? should i flush the trans and put in some gl-4?

 

Use gl4 in the transmission and gl5 in the diff.