How do you know if you need to change your transmission fluid?
Transmission fluid is one of the important fluids to keep your vehicle running smoothly. The others are engine oil, coolant, power steering fluid, brake fluid, and windshield washer fluid. You should probably also consider gasoline as an important ingredient, but it’s not exactly the same as the others, since its main function is as a fuel, not a fluid, for the health of your engine and transmission.
In today’s blog, we’ll focus on transmission fluid, but more importantly, we’ll explain how to know when it’s time to flush out your old transmission fluid and replace it with new. First, let’s understand some background information about transmission fluid and its function in your vehicle.
What is gear oil? What does it do? Transmission fluid is responsible for properly lubricating the major mechanical parts of your transmission, keeping the system cool at the right pressure, and preventing oxidation that causes rust. If the oil is not functioning properly, your entire transmission can literally grind to a sudden halt. The lubricating and cooling effects it produces are especially important.
Transmission fluid circulates through the moving parts of the transmission, similar to the motor oil that circulates through an engine. It simultaneously lubricates and cools, preventing unnecessary friction and the severe wear that such friction can cause. Like motor oil, it is introduced into the system fresh, has a smooth, silky consistency, and a deep, rich red color. As we’ll explain below, these are key factors in knowing when to change the fluid.
Over time, the fluid flushes and filters out metal shavings caused by the movement of interconnected parts, as well as other deposits and contaminants caused by the normal operation of the transmission system. There comes a point when the fluid becomes so contaminated that it no longer functions as intended and needs to be replaced.
However, there are factors outside of the normal life cycle that can trigger the need for a transmission fluid flush and replacement. In the next section, we will discuss all the signs.
Signs that your transmission fluid needs to be changed
Below are the most obvious and most common signs that indicate that your transmission fluid needs to be changed.
1. 30,000 – 60,000 miles remaining
The average lifespan of a transmission fluid reservoir varies by vehicle and year, but is typically between 30,000 and 60,000 miles. If you find that you’ve driven 30,000 miles since your last transmission fluid change, it’s worth doing a few checks to ensure the condition of your oil.
For many drivers, this is a simple DIY job of removing and checking the transmission fluid dipstick. Again, this works similarly to engine oil. Drivers can use the dipstick to determine if the fluid has turned brown/orange or if the fluid has become particulate and contaminated. When the fluid loses its rich, smooth red color, it’s time to change it. If you’ve exceeded the 30,000-mile limit, it’s a good time to perform this check.
2. Mechanic Recommended
If you receive a recommendation from your mechanic during your transmission service, it’s best to follow it. If you’re worried that the mechanic will change your fluid when it’s not necessary and charge you extra, consider the previous point. By the time the mechanic recommends this course of action, has it been more than 30,000 miles since your last fluid change?
3. Having trouble changing gears Another classic sign is if your transmission has trouble shifting between different settings and/or if your car seems to lag when changing gears under acceleration. An effective automatic transmission should provide smooth, seamless shifts, especially those manufactured in the last decade, especially the more advanced transmissions such as VW’s DSG system. Delays are usually very noticeable. If you feel them, contact a mechanic or check your oil dipstick.
4. There is excessive heat or a burning smell
If your transmission fluid is faulty, friction in the transmission increases, which creates even more heat. You may also feel excessive heat rising inside the car around the gear lever or smell something burning. In either case, you should slow down and pull over to the right to check.
5. Engine whine when cornering
When cornering, the transmission needs to seamlessly shift again to compensate for the change in speed and traction, but if it needs fluid, it will work harder and may cause excessive engine noise or whine every time you go around a corner. This excessive noise should be immediately noticeable.
6. You See a “Check Engine” or Other Warning Light
If your dashboard gives you the “Check Engine” or other engine/transmission warning light, it could well be because of a need to flush and change the transmission fluid, especially if it occurs in conjunction with another factor mentioned in this list.
7. You Have a Fluid Leak
Wherever your car has been parked for any period of time, check to see if there are any signs of puddles underneath the vehicle. If you notice a red fluid puddling under the car, then you have a transmission fluid leak. Other colors of fluids can indicate other leaks — e.g., green is likely engine coolant — and any leak is bad news. If you are leaking transmission fluid, then either drive very slowly and carefully to a nearby garage, or call out a service to tow your car there.
Conclusion: Most Critical is Regular Servicing
From the above set of important signs, you should be able to surmise that the best way to protect your transmission and keep it running smoothly is to make sure that you have it serviced annually. Proper servicing is the best defense against breakdown when it comes to the transmission.
Your car’s transmission is a complex system and is therefore hard for even a skilled enthusiast to repair by themselves.
