CarTalk.com Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Check transmission fluid at operating temperature?

I’m almost embarrassed to ask this, but here goes . . . . How do I check the transmission fluid on a 2001 Saturn SL1 with an automatic? Is the engine supposed to be at operating temp before pulling the dipstick? I ask because I changed the transmission fluid and filter this weekend. I refilled it by adding about 4 quarts of Dexron III, starting the engine, shifting through all gears, and shutting it down. It took almost another quart after that to reach full on the dipstick. I took it for a test drive, and it’s a good thing I did that, because the filter came loose and I was loosing fluid at a slow drip rate. I took everything back apart, made sure I hadn’t double-gasketed it, tightened up the filter and let the car sit overnight. Took the car for another test drive tonight, went about 4 miles. No sign of any leak at this point. Checked the fluid and it was just above the “max full” mark. Four more miles later, I arrived home and checked things again. Still nothing leaking, the filter remained tight. At this point, though, the fluid read at the “ok” mark. I spent maybe 5-7 minutes putting the air filter box and other assorted tubing back together (the filter’s a spin-on and access is gained only after removing these components) and checked the fluid one more time. Now, it was down to the “add” mark. I don’t know which is the more accurate reading, the one immediately after driving four miles, the one immediately after an 8-mile round-trip, or the one I took maybe 5-7 minutes afterward? I always thought one checked engine oil when cold and transmission fluid at operating temp. Please do correct me if I’m wrong. I appreciate any guidance here.

I don’t know the answer. But, check the dipstick. Some manufacturers print the instructions on it.

That older Saturn automatic is an odd one. The 91 to 2002 cars had a 4 speed auto that was basically a hydraulically shifted manual with a torque convertor. Look in the manual t see what they recommend but most all other automatics should be checked hot.

I have found that some manuals do and others do not making clear whether to check it hot or cold, engine running or off.

It should explain that in the owners manual. If you don’t have one, you can probably Google and download a copy. It’s probably similar to my truck. Here’s how I do it.

Do this with all the accessories off, including the AC. Drive for 15 to 20 minutes, some on the freeway, then park on a level surface, apply parking brake. Keep engine running, in P. Move the gear selector through all the gears, one at a time, letting each one engage for 10-15 seconds, then return to P. Engine is still running. Now remove the dipstick and wipe it off, then reinsert, don’t wait long, just pull it back out. Look at the fluid level on both sides of the stick. One will be lower than the other. Use the lower one. Ignore spots that have splashed higher up on the stick. The level should be between Max Hot and Add Hot, usually there’s a crossed hatched area on the stick for that level range.

On some vehicles that can be used for towing, not sure if that applies to an SL, but for those kinds of vehicles there are sometimes marks higher up on the stick to use for towing applications.

Thanks for the responses, folks. I’m guilty of the cardinal sin for an automotive forum. I didn’t read my owner’s manual first. I’m surprised, but the manual contains a very detailed description of how to check the transmission fluid. If anyone ever needs the “official” Saturn procedure for a transmission fluid check on a 2001 SL1, here it is . . . vehicle should be at normal operating temp, between 190 and 200 degrees Fahrenheit. Drive 15 miles when outside temps are above 50 degrees Fahrenheit, longer if colder than 50 degrees. Park and shift gear through all positions. Let engine idle for 3 mins with accessories off. Pull dipstick, wipe, reinsert, and pull again. Fluid should be no higher than “max hot” line.

1 Like