Just wanted to post that I'm about to switch to 75w-140 syntheic gear oil in my trans.. I'll post my results but I've always heard it can increase mpg and during winter days make driving not feel like your towing something for the first 2 or 3 minutes.. I got everything to do it so I'm more then likely switching tommorow.. I'm pretty sure going from 80w to 75 shouldn't hurt anything.. But anyway just wanted to tell you all incase any of you all are thinking about it..