Switched to synthetic in the rear end
Sucked the dino **** out of the 125k mile rear end. I was averaging about 22 mpg.
Refilled it with Alisyn Pro Gear Type 3 (their thickest gear oil, has a consistency close to water).
Driving to and from work, same roads as before, same gas stations, same kind of driving, with driver window down I averaged just about 26mpg.
I am impressed.
Those with old gear oil, switch to synthetic.