How to Change Gear Lube?

You can't complain about the years of service your old 4x4 pickup has put in. It has done yeoman duty, day in and day out. In return, you've been more than happy to do much of its maintenance yourself. Now, perusing the lubrication schedule in the owner's manual, you see it's time to change the lube in the manual gearbox.


The manual calls for fresh lube in the axles and the transfer case, too. Looks like it's time to get a little dirty.

Going to the Well

Step one is to get the appropriate amounts of the right lubricants. Manual transmissions use 80W-90-weight gear lube, right? Uh, not always. Some

manufacturers actually use automatic transmission fluid. Read that again, slowly: Your manual transmission might be filled with ATF. The advantage of ATF over gear lube is its thinner viscosity, which means less drag and, consequently, improved fuel economy. Appropriately, the gears and bearings in transmissions that specify ATF are engineered to use the thinner lube. So, don't think you can save yourself some gas by putting ATF in your manual transmission unless it was designed for it.

Read the lubricant specifications page of the owner's manual carefully--if your manual transmission takes automatic trans fluid, you'd better know which ATF. These days there are nearly a half-dozen types of fluid on the market. There is no such thing as a universal fluid. Wait, it gets even weirder: There are at least a few manual gearboxes that are supposed to be filled with engine oil. So read your manual, don't ask too many questions, then buy and use what is specified.