By Tom Morr
Vehicles' vital fluids normally perform two important functions: lubricating and cleaning. As the fluid circulates through the parts, it gathers the dirt and metal shavings that can accumulate over time. If you're lucky, this debris will settle on the bottom of the pan or housing and not circulate through the system. That’s why some auto shops use machines that perform a transmission fluid flush, ensuring that more of this debris is removed before any new transmission fluid is poured into the vehicle.
Nothing prolongs vehicle life more than regular fluid changes. In automatic transmissions/transaxles, the recommended service interval is about every 30,000 miles or 30 months. (Check your owner's manual or service manual for your car's specifics.) The automatic transmission fluid (ATF) should be changed sooner if its dipstick reveals dark or burnt-smelling fluid.
DIY transmission fluid and filter changes
Even those of us who change our own oil often cringe at the prospect of draining ATF. Because many transmission pans don't have drain plugs, changing the fluid can be a messy proposition –the entire pan must be removed. But even on vehicles that do have drain plugs, the pan still must be removed to change the filter.
Changing transmission fluid is one of those messy jobs that someone has to do. Doing the deed yourself will save money, possibly time and fresh ATF can make your gearbox perform young beyond its years. It’s also relatively easy to determine when your ATF may be low. Consider an automatic transmission service if you detect the following signs of low transmission fluid:
- Transmission slips
- Transmission shifts roughly
- Noisy transmission
- No drive engagement in forward or reverse gears
How to change automatic transmission fluid: Step-by-step instructions
If you can garner some initial patience, learning how to change automatic transmission fluid will only benefit you in the long run. More importantly, you’ll need an automatic transmission filter kit; they normally contain a gasket for the pan in addition to the new transmission filter and its O-ring. Along with some basic shop tools, you’re ready to get started.
Step 1: Transmission fluid drains better at operating temperature, so let your car idle for a few minutes first. After turning your ignition off, raise and secure the vehicle. Then, lay down a tarp, some cardboard or a newspaper under at least a two-gallon catch pan. Next, remove the bolts from one side of the transmission pan, being cautious of hot exhaust parts and fluid.
Step 2: Gradually loosen the other bolts, which should allow the pan to tilt and begin to drain. Once all bolts are removed, lower the pan and dump the remaining fluid into the catch pan. Gently break the gasket seal with a screwdriver, if necessary.
Step 3: Clean the gasket surfaces on both the pan and the transmission housing. Inspect the pan for metal shavings or other signs of internal damage, and then clean it with solvent.
Step 4: Remove the old transmission filter and O-ring. The filter contains fluid, so keep the drain pan underneath.
Step 5: Install the new transmission filter, making sure that its O-ring seats in the appropriate orifice.
Step 6: Attach the new gasket to the pan with oil-soluble grease –not gasket sealer or adhesive.
Step 7: Refer to the service manual about using thread sealer on any or all of the transmission pan bolts, then screw in all fasteners finger-tight.
Step 8: Torque the pan bolts to spec in a spiral pattern starting at the center. Maximum torque is often about 12 pounds per foot.
Step 9: Lower the vehicle and fill the transmission with the recommended amount of fluid.
Step 10: Start the vehicle, warm it up, then shut it off and check for leaks. If you don’t detect any leaks, run the vehicle up to operating temperature on level ground, move the shifter through all gears, return to park and check the dipstick while the engine idles.
Always practice good safety behaviors when working on motor vehicles. To help prevent injuries, use appropriate personal protective equipment, which may include safety gloves, goggles, helmets and shoes.
Most vehicle owners know that in order to keep their ride roadworthy, they need to stay up-to-date on routine maintenance, such as oil changes and tire replacement. But you should also keep tabs on your automatic transmission—you know, that thing with the gears that you shift into drive, reverse, and park multiple times a day. Keeping your transmission humming smoothly can pay dividends, as it's one of the most expensive components on your car to repair or replace.
Thankfully, checking on your transmission's health is neither as difficult, as time consuming, nor as costly as you may think. Here's how.
Checking the Fluid
Just as your engine uses oil to lubricate and cool its internals, automatic transmissions use specially designed transmission fluid for the same purpose. Conventional automatic transmissions, dual-clutch automatics, and continuously variable automatic transmissions each use a specific type of transmission fluid. If you're unsure which fluid is used in your transmission, consult your owner's manual; typically, transmission-fluid requirements can be found in the specifications section.
You don't need to be a mechanic to gain insight into the condition of your vehicle's transmission—a simple visual check will do. You'll need to look at the level and condition of your transmission fluid.
Locate the Dipstick
First, locate the transmission dipstick, which can be found under the hood, in the engine compartment. Make sure you are locating the transmission dipstick and not the engine-oil dipstick; the transmission dipstick is usually
further back in the engine bay, toward the firewall (the bulkhead at the front of the cabin). The transmission dipstick is typically marked with a specific color or a transmission symbol.
Note: if you can't find the dipstick, don't be alarmed. Many modern vehicles use a sealed-for-life transmission that never requires checking or fluid replacement—so they don't have a dipstick. (Refer to your owner's manual for your model's specific service schedule and to double-check whether it has a transmission dipstick.)
If your vehicle has a sealed transmission, you can slam the hood shut and drive. But if your vehicle does have a transmission dipstick, here's what to do next:
Check the Level
With the engine warmed up, leave the car idling in park on a level surface. Pull out the dipstick, wipe it clean, replace it slowly, and then pull it back out. Check the fluid level—how high the fluid comes up on the dipstick—against the "full" and "low" or "fill" marks on the dipstick.
The color of transmission fluid can tell you a lot about the health of your car's transmission.
Fluid Condition
Now lay the dipstick on a white surface, such as a paper towel, to analyze the color of the fluid. The condition of your transmission fluid—and to some extent, the transmission itself—is indicated by the color of the fluid. If your fluid is healthy, it should have a reddish-pink color; if it's getting to the point of needing replacement, it will be brownish red. If the fluid is dark brown or black, then it's quite possible that you will be replacing more than just your fluid. Dark fluid with a burnt smell is bad news; in the worst case, you might find fine metal shavings in the fluid as well. Both of those symptoms point to possible damage of your transmission's internal components. This is usually a result of failing to follow the recommended service interval for replacing the transmission fluid, but it's not impossible that a transmission could have a premature mechanical issue, just like any other component on the vehicle.
Low Fluid?
If your fluid is low, it doesn't necessarily mean you're headed for disaster, but it does most likely mean there is a leak somewhere in the system. Filling up the transmission and then checking it daily to see how quickly the level goes down can be a good way to assess the severity of a potential leak. Also try to visually inspect your transmission by looking under the car for any fluid oozing out of it. Does the car leave spots of reddish fluid on the ground after it's parked? If the fluid is black, it's engine oil. If it's water, it's likely condensation from the air-conditioning system.
If you do notice some transmission-fluid loss or observe that your transmission is using an abnormal amount of fluid, contact a mechanic as soon as you can. We'd recommend seeing a reputable car dealer who sells and services your vehicle as a first stop. Its service department will have the most experience with your make and model and might have seen this issue before. If you have the luxury of letting the car sit until it can be inspected, do so.
Contrary to what some internet mechanics may tell you, a transmission-fluid replacement will not destroy an older vehicle's aging transmission. Typically, when a transmission suddenly has issues after fluid replacement, it's because there was already an internal problem, such as a worn clutch pack. If your transmission is healthy, then a fresh change of fluid will only help its longevity.
FYI, if your transmission fluid is low and needs topping off, this is usually done through the same tube that the dipstick fits in. Adding fluid (which is available at auto-parts stores) will require a funnel with a narrow—and most likely long—spout.
Just like any machine, a transmission needs proper maintenance in order to operate as the manufacturer intended. As they say, take care of your transmission, and it will take care of you.
This content is imported from poll. You may be able to find the same content in another format, or you may be able to find more information, at their web site.
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This content is imported from poll. You may be able to find the same content in another format, or you may be able to find more information, at their web site.