Howdy all. I've got a quick question about the type of oil that should go in a Dana model 20 transfer case. The manual calls for "straight mineral oil SAE-90" but it seems that isn't produced anymore (or available under that name). What type of oil do y'all use? Can a standard 90 weight gear oil be used? My Internet research indicates that "straight mineral oil" is the same as GL-1 gear oil, but I can't find it anywhere (auto parts stores, farm stores, oil companies). Is there an online retailer that sells this stuff, or is there an off-the-shelf replacement?