Hello, I am looking for a GL4 gear oil for my Muncie transmission and am wondering what are all the non synthetic (Dino) GL4 gear oils that are out there in the market? The only 2 that I found searching the internet is Pennzoil GearPlus (which I was just told by Pennzoil is discontinued and they only have GL4 synthetic now) and Sta-Lube at Napa which i have never heard of and don't know much about its quality. Are there other non synthetic gear oils our there that I am not aware of and aren't difficult to track down. Is the Lucas HD 80w-90 gear oil synthetic? I know there are a few synthetic GL4s on the market like Redline, Royal Purple, Amsoil, but other then RP they are all a thinner viscosity and am worried that they will start to leak in my Muncie trans. All I am finding from most of the manufacturers are GL5s, but from what i read i am not the only one looking for dino GL4 gear oil, not sure why no one seems to make it anymore if there are still lots of transmissions out there that need it. thanks for the help