The oil level of the main transmission is checked via the ______ ______.

• A. Dipstick
• B. Sight glass
• C. Oil gauge
• D. Reservoir cap

Answer: (B)

The key idea is that many main transmissions use a sight glass to show the oil level directly. A sight glass is a transparent window built into the transmission housing that lets you see where the oil line sits relative to the markings. When the machine is on level ground and the oil is at the proper operating temperature, the fluid should line up with the indicated mark in the sight glass. If it’s low, add oil through the fill port until the level reaches the mark; if it’s too high, drain to the correct level. This method avoids opening the system and keeps contaminants out, which is why it’s preferred for checking the level. The other options aren’t used here because a dipstick isn’t typical for sealed main transmissions, a reservoir cap is not a level indicator, and an oil gauge isn’t the standard visual indicator in this setup.