Transmission Service

How often is it necessary to have transmission service done on a vehicle? Also, what sorts of questions should I ask the mechanic when I get this done? I’ve asked around about it, but the prices seem to fluctuate a bit too much. Sometimes it’s $90, sometimes it’s $130. I understand there are some instances where a filter needs to be replaced. Is that where the price difference comes from? If so, how necessary is it to change the filter.

I’m fairly mechanically inclined, but I just recently started to get involved with working on my own car. I’m not sure if a transmission service is something simple like an oil change, or something I could get away with doing on my own fairly easily.

Any input would help.

What year is your Lumina?

In general, official manufacturer recommendations for servicing transmissions are all over the map. You should know what the official recommendation is for your car. It’s someplace in the owner’s manual.

However, many professional transmission techs think that almost all of those recommendations are bonkers because they either give very long intervals or try to pretend it doesn’t need to be serviced. The consistent recommendation I’ve been given by transmission techs is to drop the pan and change the filter every 30K miles. (This applies to your Lumina).

The other thing shops might want to do is “flush” or “fluid exchange.” A pan/filter service only gets about half the fluid. The other method does 100% of it. BUT, doing that without changing the filter is…well, kind of dumb.

On the cost, you can just expect to pay between about $90 and 130 for the service. On this kind of thing I would use a dedicated locally owned transmission shop or dealer service dept.

Most people start asking when they’re having a problem - and by then it may very well be too late. Fluid service is preventative - and prevent is all it can do. On some occasions it can help with some kinds of problems, but don’t expect too much.

I’m a mechanic. My recommendations for transmission fluid service are to drain the fluid and replace the filter (if applicable) at 30,000 mile intervals. I use only the correct manufacturer approved fluid, not the bottle at the parts store that says “suitable for most cars.” You can do this yourself if you don’t mind the freakin’ mess of laying on your back in a puddle of trans fluid since there are usually no drain plugs on GM cars. You just have to pull off the trans pan while it’s full of fluid and hope you hit your drain pan.

Many cars now state that no service is required for the life of the vehicle under normal driving conditions. That may be true, and I will agree with that if you lease your car or trade-in every few years. But the fact is transmission replacement can easily run $3500 or more these days. An average fluid and filter service is $150. Seems like money well spent.

+1 for @asemaster .

U never know what fluid is in a used car. My Taurus sez use merc V. Do not use merc 3 stuff. Right in manual. And it’s an 02. Certainly not new. So, change ur filter and put in some proper fluid.

As a DIY trans pan dropper, the mess is usually controllable. It’s mostly a matter of strategy so that only one end of the pan will drop enough to have most of the gush funnel itself out in one direction rather than all over the pan. I normally do it on ramps. You need a large, short tub to use. I just have a basic plastic storage container meant to fit under an average bed.

On ramps the pan is tilted to the rear of the vehicle and you use that to your advantage. I first pull all of the bolts on the rear of the pan, except for the corners. I loosen those and then barely snug them back down. I then loosen up the sides of the pan toward the front. If it’s not oozing yet the rearmost sides come out, and toward the front just left about halfway out. I loosen and then barely snug the ones at the front last. If the thing is already leaking fluid by then (often it’s so stuck on that it’s not) I hold it on with one hand and remove the two rear corners. The pan should then tip enough so that most of the gusher will then get funneled out the back into the tub. To finish, after the major gusher, hold the pan up to the mating surface and remove the rest of the bolts. The pan is mostly empty by then, but then you just lower it down and dump the rest. It’s messy, but when I recently did this on my caravan I made little to no mess outside the tub.

I also like to then add a drain plug and there are various ways of doing that intelligently including little kits that require no special tools or materials other than a drill and some threadlocker. You also need enough common sense to not install the plug where anything internal might interfere with anything on the bottom side of the transmission

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Many cars now state that no service is required for the life of the vehicle

That always amuses me, because they never tell you what the expected life of the vehicle is. That statement would be true about any maintenance. “You don’t have to change the oil for the life of the vehicle. We… Kinda left out the part about the life of the vehicle being reduced to less than 40,000 miles if you follow our advice, but it’s still the life of the vehicle!”

I think that a 30K service interval is a little more than necessary unless the vehicle is used in severe service (trailer towing or stop & go delivery, taxi). For today’s transmission designs, every 50K miles should suffice…But there are so many different transmission designs out there, there are no hard and fast rules…Many new models have CVT-type transmissions that require careful adherence to the recommended service intervals…This proliferation of transmission designs has led to a proliferation of ATF types needed to service these transmissions…Claims that a particular fluid is “Universal” need to be taken with a grain of salt. To protect long-term power-train warranties, it’s important to use the factory specified transmission fluid…

Most automatic transmissions have an internal oil filter and to do the job right, this filter should be changed when the fluid is changed. Shops advertizing a “Transmission Flush” usually neglect doing this, claiming it’s no longer necessary…But a restricted filter can lower internal fluid pressure which can lead to slippage and erratic shifting. In a perfect world, the pan should be dropped and the fluid changed, then the flush machine hooked up and ALL the fluid changed…

If anyone is still following, my vehicle is a 98 Lumina. I am not having any issues with it now (in fact, this car is actually amazing. It has almost no rust spots and I take excellent care of it).

When the car was my father’s, he had the transmission service done back in 2006, which I believe included the flush and filter. This year he started doing that fatherly grin, elbowing me in the ribcage, telling me it was about that time again.

I agree with Caddyman regarding service interval IF the recommended fluid is fully synthetic (many are AFAIK).

I’m wondering if I should just tell the shop to replace the filter anyways. Before I moved to Indiana, our tried and true shop back in Michigan said they didn’t replace the filter unless it looked worn out. I can tell you I’ll feel a whole lot better if I get at total flush and new filter.

And for the record, if there is any mess involved, I’d better just take it in to a shop. My landlord, though a very nice guy, is also a clean freak and I can’t even imagine what would happen if I spilled anything in his precious parking lot.


You said you’re fairly mechanically inclined

I think a transmission fluid and filter service should be well within your comfort zone

Large drain tub
3/8 ratchet
short extension
gasket scraper
transmission fluid funnel
10mm or 13mm socket, I believe
Dexron atf . . . I don’t know how much you need
filter and gasket kit

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Given the landlord, yes you probably should just take it to a shop. I would just have the pan dropped and filter changed. Changing it only it it “looks worn out” is bizarre. A new filter is cheap. IF the pan comes off anyway, it’s absurd not to stick a new on on there. Shops that say things like that are usually trying to sell a “flush” instead. Flushes are cash cows since all they do is hook it up to a machine and turn on the dumb machine.

An extra advantage to having the pan dropped is that inspection of the contents of the pan provides really important info about how the transmission is doing. A lot of trans shops will drop the pan as part of diagnosis. Of course, in this case, the person dropping the pan has to be a fairly experienced transmission tech - otherwise they don’t really know what they are looking at.

Speaking of flushes

A flush isn’t going to do anything to address that dried up and leaking pan gasket . . .

“Speaking of flushes
A flush isn’t going to do anything to address that dried up and leaking pan gasket . . .”

Another good point. I actually love pulling a pan. I get to see inside of it. Of course, sometimes that stinks (as it always did on this Silhouette that I used to have), but then at least you know. I then also get to give it a clean filter and fresh gasket, torqued to spec…which I should have mentioned. If, for whatever reason you do end up dropping your own pan, the two biggest things that contribute to long term success are 1) the right quantity and spec for the fluid and 2) correct torque on the pan bolts. Messing that up will give you leaks. It’s also pretty easy to damage those threads in what are normally aluminum cases.

I’d rather keep my experimental projects to power windows and switches for the time being.

Speaking of aluminum cases . . . I’ll go a little off topic here

I had to helicoil the transaxle case on my brother’s car

I was the only one who had ever serviced the transmission over the years

I never crossthreaded the pan bolts, but the threads in the case were literally so worn out that some of the bolts actually fell out!

The case was aluminum, so that is probably the explanation for the worn threads

After the repair, I installed a fresh filter, cleaned up the pan and installed a new gasket

I started every bolt by hand, then I torqued them all to spec. No problems there.

I might add that I actually supported the drivetrain from up top and removed part of the cradle, so that I had a clear shot at my repair. It made a big difference. Sometimes removing a few things actually makes the repair easier

I had to do some on an old '95 Caravan I had. I can’t say what happened with the pan before I owned it, but I may have contributed to the problem because the threads in the case and the bolts were fairly gunky and I didn’t really spend any time cleaning it up. It’s a while ago, but I think all I did was rinse down the bolts with some brake cleaner. Anyway, I’m never all that unhappy with the helicoil in the aluminum. It’s actually much stronger then. And I never start a pan without having the thread repair stuff on hand … just “in case.”

Just a thought, but if you have this transmission service performed by someone else you could ask that a drain plug be installed into the transmission pan while it’s off.
In the future, that could really deter any mess if you decide to DIY and could make a partial drain and fill a piece of cake.