When Do I Need to Change my Transmission Fluid?

By Chantel Wakefield 05/22/2023 4:00pm

Quick Facts About Transmission Fluid

Transmission fluid is needed to lubricate the parts inside of an automatic transmission.
Change your transmission fluid and filter according to the manufacturer recommendations outlined in your owner’s manual.
Fresh transmission fluid is pink or red. Dark or rusty fluid indicates a problem and needs prompt service.

Some vehicle maintenance questions have simple answers. Change your oil as the manufacturer recommends, and your engine may deliver 200,000 or more miles of service. Neglecting to regularly change the oil and filter can reduce your engine’s long-term health. The result: Large repair bills.

The same is true for your automatic transmission and its fluid. Regular maintenance is the key to transmission longevity. If you are looking for a clear answer to “When to change to change transmission fluid?”, we can say that recommendations vary by manufacturer and model. Below we have best practices, instructions on how to check transmission fluid, and more.

What Is Transmission Fluid?

Transmission fluid is a lubricant that keeps automatic transmission components running smoothly. This fluid is usually made of mineral oil or a synthetic blend with additives to prevent corrosion and oxidation. It’s crucial for the performance of the entire system, which sends power from the engine to the wheels. Automatic transmissions instinctively shift gears as you speed up and slow down, and the fluid helps make that shifting smooth.

When To Change Transmission Fluid

As mentioned above, recommendations and fluid flush intervals will vary by vehicle make and model. For example, guidelines for the 2023 Honda Accord indicate the dealership service center will check the fluid and “replace if necessary,” while the owner’s manual for the 2023 Nissan Altima advises transmission fluid replacement every 60,000 miles. Always follow the manufacturer’s maintenance schedule to comply with the warranty and maximize the life of your vehicle.

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How To Check Your Transmission Fluid

Locate the dipstick. Many vehicle owners will be familiar with automatic transmission dipsticks, commonly located near the back of the engine under the hood.
New automatic transmission fluid is generally pink or red. If your transmission has a dipstick, take a sample and wipe it on a white paper towel to see if it looks fresh (pinkish or reddish) or is something less favorable.
Dark red, rusty, or black means your transmission needs attention. You should immediately go in for service if the fluid has flecks of metal in it because an internal transmission component is likely failing.
A foamy, bubbly-looking fluid means that the transmission could have been overfilled — or something worse. Again, immediate attention is vital.

Note: Some newer vehicles do not have dipsticks for transmission fluid. The fill point is under the vehicle on the transmission near the pan. If you can’t find the dipstick, reviewing the fluid level and coloration will be difficult. Take it to a professional repair shop or franchised dealer in these cases.

Transmission Fluid Maintenance

If you have a new vehicle or one with service records showing regular transmission fluid changes, continue to do the fluid and filter changes recommended in your vehicle owner’s manual. A qualified service technician should flush and refill the transmission. You should change the filter at the same interval to avoid plugging up and causing fluid starvation.

Flushing is the process by which the new, fresh fluid forces out the old, using the transmission’s pump to do the pushing. The transmission pan (the pan on the bottom side of the transmission) holds only one-third to half of the fluid. A large amount is stored in the transmission’s torque converter. So, just for the record, simply emptying the pan is not a proper fluid change.

During service, technicians replace the fluid and filter. They also retorque the transmission valve body bolts and install a new transmission oil pan gasket to avoid any leaks. Expect to pay $200 to $300 for a transmission fluid change. The preventative action is worth the cost because rebuilding a transmission is much more expensive.

Signs You Need to Change Transmission Fluid

Difficulty shifting gears: If you have a tough time shifting gears, specifically when shifting from a lower gear to a higher gear, it may be time to change the fluid.
Slipping gears: If the transmission is slipping out of gear as you drive or takes too long to engage, the transmission fluid may be low. This means it’s time to change the fluid.
Rough or noisy shifting: If you notice that the transmission jerks or shifts loudly, the fluid may be old or contaminated.
Transmission overheating: Your transmission temperature gauge should hold steady in the center. If it’s overheating, the fluid may not be cooling the transmission properly.
Dark fluid: If you check the dipstick and the fluid is dark or smells burnt, it’s time to change the fluid. This can also indicate a bigger issue, so have the entire system checked by a certified mechanic.
Leaking fluid: If you notice fluid leaking under your parked car, it might be from the transmission. Have it checked before the reservoir gets too low.
Poor fuel economy: If you notice a dip in fuel efficiency, the transmission may not be operating as it should. While many factors contribute to your overall gas mileage, a fluid change might help improve performance.

MORE: Why Is My Check Engine Light On?

Hazards of Deferred Maintenance

With automatic transmissions that have not been serviced for tens of thousands of miles or have no history of service, replacing the old lubricant with new transmission fluid can cause transmission failure in some cases. This is because the foreign matter floating in that old fluid (it’s mostly clutch material) may create the friction that’s helping the internal clutches find their grip.

If you pour in new clean fluid, it washes that matter away, and the internal clutches begin to slip. This is especially true with vehicles with more than 100,000 miles and no record of regular transmission fluid service.

Don’t delay changing the transmission fluid according to the vehicle’s maintenance schedule. Keeping up with the task every 50,000-60,000 miles, if that’s what your car requires, may help you avoid reaching the point where the fluid is so dirty it can’t lubricate the gears.

Regular Maintenance a Must

Ensuring your fluid levels are on the mark and keeping regular maintenance schedules will help your transmission deliver well over 100,000 miles of trouble-free service. Transmission rebuilds are not cheap, in the range of $4,500 to $6,000 or even more, depending on the make of your vehicle.

A rebuild requires removing the transmission from the vehicle and assembling it with factory-approved components. Some shops and dealerships suggest installing brand-new transmissions rather than rebuilding them. High-tech variable ratio transmissions, such as those Honda and Nissan commonly use, generally require full replacement due to their complexity.

MORE: Why Do My Brakes Feel Spongy?

Extra Transmission Fluid Tip

If your transmission is slipping from time to time, but the fluid appears clean, you can try several “Stop Slip” additives. As noted, overfilling an automatic transmission is a bad idea, so you have to remove about a pint of fluid from the system before pouring in the additive.

If you have a dipstick, you can purchase an aftermarket pump that will draw fluid out of the dipstick tube with a plastic hose. Sometimes, this helps reduce slippage, but don’t kid yourself, you’re only buying time.

Like it or not, your transmission will require service soon. It’s money well spent. Find out how much a transmission fluid change costs in your area for your vehicle.