Manual Transmission Fluid
Fluid checks and changes should be performed at regular intervals according to the vehicle manufacturer's recommendations and specifications. If the transmission is operated under severe conditions such as heat, cold or dirt; it should be checked and changed more frequently. Changing poor transmission fluid can improve shifting and extend the life of the transmission.
Check the fluid for condition and level through the transmission drain plug. Check with specifications if unsure about the fill and drain plug locations. Many drain plugs incorporate a magnet to collect any metallic debris circulating in the fluid and collecting in the sump. Inspect and clean these drain plugs before replacement. Fill the transmission to the base of the fill plug opening.
If excess metal is found on the plug and in the oil, it's most likely from worn gear teeth. Synchronizer blocking rings are often made of brass. Because brass is not magnetic it will not show on these magnets, but will show up as the fluid is drained. If brass is found towards the end of the draining cycle and the vehicle is suffering from hard shifting, the blocking rings are likely worn. In order to replace damaged blocking rings, a transmission overhaul is in order.