How to Stop Leaking Transmission Fluid

Pouring transmission fluid into an orange funnel.
What You'll Need
Transmission dip stick
Transmission Stop-leak
Owner's manual

Transmission fluid is one of the most important components for a vehicle to function properly. It helps with gear lubrication, valve operation, torque conversion, and brake friction, so you can imagine all of the parts that can begin to break down when your fluid runs dry. Checking the dip-stick every 25,000 miles should be suitable for maintaining your levels and ensuring that there is no dirt in it from natural wear and tear, but if you have a leak, the situation will need your attention long before then! Read through the information below for advice on how to identify a leak and fix it quickly.

Tip: In the case of manual cars, owners should regularly check for transmission fluid contamination. This is due to the wear and tear of metallic parts in constant use. Sometimes, metallic particles end up in the fluid and can affect its ability to lubricate the parts. Conversely, in automatic cars, the transmission fluid is prone to degradation due to heat generated during use. It then loses the ability to lubricate and gathers contaminants.

Step 1 - Inspect Transmission Fluid

A transmission dip-stick is used to check the fluid level in the car. If the marker is below the full line, it should be topped off. Make sure your car is parked on a level surface, not at an incline, before you test or your results could be inaccurate.

If your fluid level is low and you know that you've recently refilled it, it's time to check underneath your car. When you're leaking fluid, a puddle of liquid will collect wherever your car is parked. Transmission fluid will be a brown or red color. If the color is green, it is probably an engine coolant leak, or if it is thin or clear, then gasoline can be the culprit.

Step 2 - Fix Depending on the Amount of Leakage

When you find only a few drops of fluid on the ground, a high-quality brand of transmission stop-leak will fix it. Find one appropriate for the make and model of the car, remove the dip-stick, and pour it down the tube. Pour enough to replace the lost fluid until the correct level is indicated.

For major leaks where a large amount of transmission fluid has collected on the ground, you can also use a stop-gap measure. However, at the end you will need to take it to the professional mechanic for a more permanent fix.

Step 3 - Take Preventive Measures

Create reminders for yourself when you should check the transmission level and condition, so it is done at regular intervals. The fluid should be changed if it's dirty and after any time period suggested in the owner’s manual; the type you will need to purchase should also be indicated in the manual. Your parking area should be regularly checked for any leaks as well.

If you have to take your car to a mechanic for a fix, you should use a repair shop at your car dealer as they should have the original parts and know exactly what is required according to the make and model of the car. This way, you are sure to get the most lasting repair. Also, when communicating with the car dealer/mechanic, you should be as detailed as possible about the problem.

Finally, note that reversing or parking should only be done after a car has come to a full stop to be as easy as possible on your gears and lower the amount of contaminants your fluid is exposed to as a result.