I change mine 5000kms, just about to do the M\T fluid...almost at 50000kms, and 75\80 is the spec, but whenever checking it the oil viscosity does not seem like 75-80. It seems a bit lighter of an oil. I am going to buy mitsu oil just to be sure. I use 80-90 on the trucks I work on and 50W for the trans, our trans oil seems more like 50W in terms of viscosity. Have anyone changed it with aftermarket 75\90 and had any issues?