Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Transmission fluid change

Hi I have a 2001 Saturn SL2 and last changed the transmission fluid at 40,000 miles - the car now has 110,000 miles on it and the transmission is working fine and the fluid looks good and is pink and smells ok; my question is - should I change it? how long does the fluid last? Please advise. Thanks, Mel

What does your owner’s manual say? Why don’t you follow that?

Many of us believe a pan drop. fluid and filter change will keep your transmission in good shape. It is good preventive maintenance. Your owner’s manual may or may not recommend change intervals, but my experience has been that these fluid changes each 30K keeps the AT in good shape.

some mechanics say if the fluid looks good and smells good to leave it alone - how long can it last -

Is it an automatic or manual transmission? Both use the same ATF. If manual, you can leave it in forever. If it is an automatic, then “some mechanics” would be wrong.

In the automatic, you cannot drain all the fluid out at once. In fact, you can only drain about 40%. You need to drain and refill periodically because it refreshes the ATF with new additives and gets rid of some (about 40%) of the contaminates. Done on a regular basis, the transmission fluid will remain good enough to last about the life of the car, unless you are going for a million miles.

If you go too long, then you need to do several drain and fills in a row or hook up to a fluid exchange machine (flush machine). Even that wont get it all out, but it will do a pretty good job. The problem is that by this time, the fluid will have degraded enough to shorten the life of the transmission.


Thanks; could flushing the transmission cause any problems?

Yes if not done correctly. The fluid needs to be drained, the pan dropped and the filter replaced or cleaned and pan cleaned first. Then after the filter and pan are reinstalled and the transmission refilled, the exchange machine hooked up to get the rest of the dirty fluid.

Right now, if I inspected your fluid and I think it is as good as you think it is, then I would consider a flush a waist of money. But it is possible that your fluid is not as good as you think, you are going to have to trust someone there who can lay eyes on the fluid to advise you.

If you can change your own oil you can service your own transmission. Just pull then drain plug and drain the transmission, reinstall the drain plug. Screw off the transmission filter and screw on a new one, fill and road test. If the fluid is still clean and healthy I see no reason for a flush.

does this car actually have a transmission pan?

I think it does, my Saturn is a manual so I didn’t buy the service manual for the automatic. I was not aware that it had an external spin-on filter as suggested by asemaster.

yes it has the external filter so would it definitely have the removable transmission pan also?

If it does, you probably do not need to drop it, the magnet will be built into the plug. Automatic transmissions with the internal filter usually have a magnet stuck to the inside of the pan to hold any metal particles and keep them from circulating with the fluid.

Metal particles are normal wear from the clutches inside the transmission so do not be too alarmed when you see them sticking off the end of the plug.

Most of the Saturn design was a result of the UMI project with Toyota. A lot of the mechanicals are very similar to a Corolla. That is why I assumed that it had the internal filter. Like I said, my Saturn (02 SL) is a manual. I bought most of the service manuals for it, but I skipped the service manual for the automatic transmission, didn’t need it. I hear that the whole set is available on one CD ROM now, and for a lot less money than the individual books. I’m not real crazy for CD ROM based manuals though. I have one for my daughters Corolla and I find it very frustrating to use.

Thanks; so since I have the external filter - is a flush necessary or is drain and fill enough to get all the transmission fluid and contaminants out?

and no pan needs to be dropped? correct

so where do the metal filings go when you have an external filter? is the plug still magnetized? just want to make sure i understand correctly? thanks for your help and patience

The only pan on your transmission is the valve body “pan” which is on the top of your transmission. You’ll never get all the fluid out by draining and filling, but since the fluid appears in good condition I see no reason to do any more than drain and fill and replace the filter.

There may be a circular magnet at the base of the screw on filter, clean it and put it on the new one.

What I do on my Subarus is change the external filter and do two or three drains and fills every 30K miles or so. I do them about one or two weeks apart to get some use out of the fluid. Put in the same amount as what drains out.

The net effect is to get an 80+ percent dilution with new fluid. That has worked well for me and is similar to what Honda recommends. No reason why you couldn’t do this on the Saturn, as I understand it.

Thanks so much guys! I appreciate your help. One more clarification - should I get it flushed? or does that sometimes cause problems?

what is a fair price for the transmission service?