I need to check the final drive gear oil on my 1994 John Deere 650G. I see a big plug with a 1/2” drive square in the middle. The plug is on the opposite side of the track and is to the far rear of the machine. I used a breaker bar and pulled the plugs. I’m assuming it’s like the differential on a car so that when it is full it dribbles out a bit of gear oil. Is my assumption correct? If so, mine is low. There isn’t any other check point on it is there? (I’m not referring to hydraulic oil, but to gear oil.)
Just to close the thread, it is full when it oozes out after the plug is full. The correct oil is 80w - 90w gear oil per the dealer.
According to the 650G operators manual it says Hygard for the finals.
Yes the Hy-Gard is recommended, but they lost indicate an alternative in the 80W-90. This is from the manual: Depending on the expected air temperature range between oil changes, use oil viscosity shown on the chart above. Arctic oils (such as Military Specifications MIL-L-46167B) John Deere HY-GARD ® is preferred. Other oils may be used if they meet the following: HY-GARD is a registered trademark of Deere & Company. • John Deere API GL-5 Gear Oil (SAE 80W90) may be used at temperatures below — 30°C (—22°F).
80W90 below -22degree F does not make sense. It is very thick at that temp. Hy-Gard would be better at that temp. Maybe 80W90 at high temps?
I bet you’re right. That was a cut and paste from an operator’s manual I found online. Thicker oil at high temps makes a lot more sense.