Depending on whether you are using a manual or automatic transmission vehicle, the transmission fluid will have different functions. On a manual or standard transmission, the gear oil serves to lubricate the gears and aid in smooth shifting. It also lubricates the clutch pads, so that these do not burn easily from friction.
On an automatic transmission vehicle, though, the transmission fluid serves an additional purpose. Since there is no mechanical clutch that works with friction, it’s the transmission fluid that acts to initially transfer momentum from the engine to the driveshaft while starting. The automatic transmission fluid therefore plays a big part in how the torque converter transfers power from the engine to the wheels at starting speeds.
Regardless of your transmissions system, a leak on your transmission will surely result in inefficiencies in your transmission system. For one, your clutch might overheat, your clutch pads might get easily worn out. Worse, your gearbox itself might overheat if there is too little fluid. On automatic vehicles, too little transmission fluid will result in shifting problems, or problems when starting from a stopped position.
Transmission fluid leaks have a few telltale signs. Here are a few ways to check for transmission fluid leaks.
Observe if there are oil slicks or drops on your driveway or garage. This will usually form a puddle underneath your engine bay.
Check your engine temperature. Low transmission fluid will usually make your car’s engine work harder, and therefore the possibility that it will work with higher temperatures. Check your temperature gauge if it’s indicating a temperature that’s higher than usual. Normally, cars work at about 90 to 100 degrees C (or about 195 to 210 degrees F), but it’s best to check your user’s manual to verify the safe range for your engine.
Check the transmission fluid level with the ATF dipstick to determine if it’s low. If it’s below the proper level (between the “min” and “max” level), top it up. Check the level again after driving around normally.
Inspect the transmission seals. If the rubber seals are dry or cracked, fluid might leak from these points.
Check the transmission fluid drain plug. This usually looks like a bolt screwed on to the transmission assembly. The plug might be loose or might be improperly seated, therefore causing a leak.
Check any transmission joints to see if these have worn seals or cracks. These are also potential sources of leaks.
If you find that your car is leaking a large amount of transmission fluid, have it checked by a professional. In case you need to drive to the garage, don’t do so with your transmission fluid lower than the minimum level required. Top it up as often as needed while on your way to the repair shop.
Also, some leaks are not visible or evident externally. Some leaks might be internal, and are best checked by a qualified mechanic. If you suspect that your transmission system is leaking fluid, attend to it right away, to prevent any bigger damages.