Where is the Transmission Oil Filler Port Located?

[OAnnie]

The transmission oil filler port is typically located on the transmission oil pan. For manual transmissions, there are generally two bolts on the transmission housing: the upper bolt serves as the oil filler port, while the lower one is the oil drain port. In automatic transmissions, there are two bolts of different sizes on the transmission pan: the larger one is the drain port, and the smaller one is the filler port. Additional Information: 1. Before replacing transmission fluid, the old fluid must first be drained by loosening the drain port screw at the bottom. However, due to the internal structure of the transmission, the old fluid often cannot be completely drained, resulting in a relatively low fluid replacement rate with this method. For automatic transmissions, it is more advisable to use a fluid exchange machine. This machine injects new fluid into the transmission while simultaneously extracting the mixture of old and new fluid until the fluid inside the transmission becomes clear. This method consumes more new fluid—approximately double the amount required for manual transmissions—usually around 12 liters. Although the cost is higher, the replacement rate is significantly better, ensuring that most of the old fluid is removed and the performance of the new fluid is better preserved. 2. Transmission fluid is a lubricant that maintains the cleanliness of the gear system, providing lubrication to prolong the lifespan of the transmission components. It offers effective lubrication even under low-temperature conditions and reduces fluid loss during demanding operations. Depending on the transmission type, transmission fluid is categorized into automatic transmission fluid (ATF) and manual transmission fluid.