How to Check Transmission Fluid

Sun West Transmissions — Glendale, AZ. Free estimates, honest diagnosis and a 3-year / 40,000-mile warranty on qualifying rebuilds and replacements.

How to Check Transmission Fluid the Right Way

Checking your automatic transmission fluid is one of the simplest ways to catch problems early. Low fluid, burnt fluid, or fluid with debris can warn you of trouble before it becomes a major repair. The process is different from checking engine oil, though, and it varies by vehicle. Always follow your owner’s manual first. The steps below cover the general approach for vehicles with a transmission dipstick and explain what to do if yours does not have one.

Before You Start: Safety First

• Park on level ground. A slope gives a false reading.
• Set the parking brake firmly.
• Keep hands, hair, and clothing away from belts and the cooling fan if the engine must run.
• Be careful around hot exhaust parts and the radiator. In Phoenix summers, engine bays get extremely hot.
• Never open a radiator cap on a hot engine.

Step-by-Step: Vehicles With a Dipstick

1. Find the dipstick. The transmission dipstick is usually toward the back of the engine bay on rear-wheel-drive vehicles or near the transaxle on front-wheel-drive vehicles. It is often marked with a transmission symbol or a different-colored handle than the engine oil dipstick.
2. Warm up the transmission if your manual calls for it. Most automatics are checked hot, after a short drive, with the engine idling. Some manuals specify a check in park, others in neutral.
3. Shift through the gears. Many manuals call for moving the shifter slowly through each position and back to park to fill passages with fluid.
4. Pull the dipstick, wipe it clean, and reinsert it fully.
5. Pull it again and read the level. Many dipsticks have separate hot and cold ranges. Use the range that matches the temperature condition in your manual.
6. Look at and smell the fluid. Wipe a drop on a white paper towel to see its color clearly.

What the Fluid Should Look Like

Fresh automatic transmission fluid is usually red or pink and fairly clear, though some newer fluids look different. Over time, fluid darkens. Here is a quick guide:

• Bright red or pink, clear: generally healthy.
• Light brown: aging fluid; service may be due.
• Dark brown or black with a burnt smell: overheated or badly worn fluid; have it inspected.
• Milky or pink and foamy: possible coolant contamination; stop driving and have it checked.
• Visible particles or glitter: possible internal wear.

Our full guide on transmission fluid colors explained goes into more detail.

If the Fluid Is Low

Transmissions do not burn fluid the way engines can burn oil. If the level is low, there is a leak somewhere. Adding the correct fluid can get you to a shop, but finding and fixing the leak is the real fix. Use only the fluid type listed in your manual, and add a little at a time through the dipstick tube with a funnel, rechecking often. Overfilling can cause foaming and shifting problems. See transmission fluid leak and our leak repair service.

Vehicles Without a Dipstick

Many newer vehicles have sealed transmissions without a dipstick. Checking these usually involves raising the vehicle level, bringing the fluid to a specific temperature measured with a scan tool, and removing a check plug to see if fluid drips out. Getting this wrong can lead to a low or overfilled transmission. If your vehicle has no dipstick, it is best to let a shop check it. This applies to many CVTs as well.

How Often to Check

A good habit is to check transmission fluid at every oil change and before long trips or towing. In the West Valley, summer heat is hard on fluid, so regular checks help. Our guide on how often to change transmission fluid covers service intervals.

What Not to Do

• Do not use engine oil, power steering fluid, or brake fluid in the transmission.
• Do not rely on additives that promise to fix slipping.
• Do not ignore a burnt smell or dark fluid if the transmission is also slipping or shifting harshly.

Let Us Check It for You

If you are unsure about the reading or your vehicle has a sealed transmission, stop by Sun West Transmissions at 6116 West Northern Ave in Glendale. We can check level and condition and recommend transmission service or further testing if needed. Call (623) 473-9800 for a free estimate.

Checking Transmission Fluid FAQ

Should transmission fluid be checked hot or cold?

Most automatics are checked warm with the engine running, but procedures vary. Follow your owner’s manual for the exact conditions.

Why does my fluid smell burnt?

A burnt smell usually means the fluid has overheated. It may be due for service, or there may be slipping inside. See burning smell from transmission.

Can I check a CVT the same way?

Some CVTs have a dipstick, but many do not, and they require exact fluid and level procedures. When in doubt, have a shop check it.