Ok, I change my oil, rotate tires, etc...but have never tried to change the transmission fluid in a vehicle. My 95 Isuzu Rodeo is starting to feel a little funny when at highway speeds, especially when going up hill. Seems to lunch forward/back a bit...It has 140,000 miles and I don't recall ever having the fluid changed, not sure this will fix it but thought I would try...can't hurt...

So, for the mechanics out there, what would be involved in doing this process, or should I take it in to a mechanic ($$$$$) I don't think I need to flush everything, just drain the fluid, replace, filter, etc?

thanks, Randy

Is this an automatic?

What was your quote to get the fluid/filter changed, Randy? You definitely have a few miles on there, I'd be changing both if you plan on keeping it for a while.(don't use a dealer though, they'll charge upwards of double) Might be a pain in the a$$ to do yourself unless the cost of a mechanic is outrageous.

By "lurch" do you mean that is seems to rev a bit then suddenly take a lurch forward, as if it were slipping a bit and then catching? I am also assuming you mean this is an automatic transmission. Also, is there any unusual noise before/as it does this?

Changing the fluid is certainly a good idea but if the problem persists or you are hearing whining noises as above, then it may need work. However, if it comes to that, try dumping a bottle of this in to it.

Molly Slip

It's not a cure but can (depending on the issue) add tens of thousands of miles to the point where you eventually have to have the transmission repaired/replaced.

HOWEVER, as with all automotive problems, your best bet when you are not sure yourself is before trying any best intentioned advice, take it to a trusted mechanic who can take it for a drive and tell you what is realllly wrong.

This is an automatic, right?

You could be just low on fluid. It's pretty easy to check the level yourself (in most cars).

Somewhere under the hood there should be a transmission fluid dipstick. It's basically like checking your oil. I'm almost positive that the last time I needed to check this, the manual for whatever car that was said the engine should be running and the transmission should be warmed up. Check the owners manual for the location and procedure on your Isuzu.

If the level is low, add whatever type of fluid that the owners manual recommends (specific brands need specific types). Your local auto parts store (AutoZone, Napa, Express AutoParts, etc, etc) should have it. That might just take care of your problem. Keep an eye on the level though, you might have a leak.

Look at the color too. Fresh automatic transmission fluid (ATF) is bright red. Almost pink. As it ages, little bits of metal are worn off your transmission and the ATF turns more brown, and eventually black. If the ATF dipstick reveals something that looks like used motor oil, you're in need of a full flush/change.

Most quick-E-lube places can do ATF changes. I want to say it's like $75, but I don't really know. Whether or not you trust them is entirely up to you. I was just at my Chevy/Pontiac dealer the other day for an oil change and I'm pretty sure that it said that ATF changes were like $99. Not too bad. You should be able to call around to different mechanics and/or dealerships for quotes. An ATF change is a pretty standard thing, so they ought to be able to quote you a price.

If it's a manual transmission, your clutch may be on it's way out.

My Volvo recommends the engine be running and you go through a specific set of steps to check the transmission fluid level on the dipstick. Check your manual.

I had mine changed in my Civic just two days ago and it did make a big difference in the smoothness of the shifting. My mechanic charged me $101 for changing the ATF, oil and wiper blades. It seemed worth it to me. I used to change my own oil and do my own brake jobs but my life is too busy now.

Amen to that! I am lucky to have such a mechanic. He even calls me a jackass when I don't treat my vehicle right (it only takes one of him to convince me).

The fluid should be checked warm and [I think] with the engine running.

And the smell is near impossible to wipe from your skin. The only thing worse is diff fluid. Just thought I'd add that in to help justify the cost of garage change.

Good point about the flush/change. If it's already black, it needs a double run through of fluid. Empty, fill with new, let it churn a bit, drain again to rinse out the crap and then fill with clean again. I mention it just so it's not a surprise when you see it on the bill or if you decide to do it yourself.

On most vehicles, its a pretty easy job. just depends where they put everything and how easy it is to get under your car.

As a mechanic, If you are noticing a surging effect it sounds like the torque converter lock up is slipping to me and a full fluid change MIGHT help or at least put off the inevitable repair for a little while. A quick way to tell if it is the converter clutch is to tap the brake pedal while it is doing the lurch/surge. Hit the brake pedal just hard enough to activate the brake switch but not so hard as to engage the brakes, if the surging stops you have found the culprit. It could also be slipping in O/D so shifting to 3rd or D or whatever you have to do to take O/D off in your vehicle, if the surge is gone with O/D out of the picture then you have an issue with the trans itself, most likely a one way clutch is not holding and an overhaul will be required. If the surging is still there then it could still be the trans and/orconverter clutch and it just isn't disengaging/working as it should, a plugged/restrictive fuel filter or worn fuel pump, plugged up injector, slight ignition misfire even, causing the surge as well as a myriad of other itmes I won't get into, but those are the most usual suspects from my experience.

I would say the easiest thing to do is to take it in for a full trans service including a flush, pan drop and filter/screen change, this way you can see if there is any debris in the pan. You can drop the pan yourself and do the filter etc, it can be a little messy if the pan doesn't have a drain plug. When you drain/remove the pain you are only draining about 1/3 of the volume out as the torque converter holds 10-14 liters/quarts on avg. and the pan hold 4-6 liters/quarts, so I would still look at taking it in for a fluid flush as well.

If you take it in for a flush it is a 1:1 fluid swap process, no fuss or mess.

And Murph is right about the smell of burnt trans fluid, it is quite possibly the worst smell there is, I think it is even worse then diff oil which comes in a close 2nd, IMO.

Sorry, been in meetings.

Ken, it is an automatic.

Adrian, I have not got any quotes yet, just heard it is expensive to have a mechanic do it. I'm fairly handy, figured I would try...

Murph, I typed Lunch and meant to day lunge. There is not noise that I can hear, just seems to be when going up hill at about 55-65 miles an hour. I'm not applying any acceleration, it just feels like it hesitates, then frees up, hesitates, frees up..

Pete, it does have a dip stick, I'll check the color tonight..

Thanks Jakewash, yes it feels like a surge, release, or a lunging experience, not real bad just enough to notice. Almost like the wind is blowing back/forth from the front/back of the vehicle.

My goodness! Speaker advice, cookie recipies, smoked meats, random headshrinking and now trannie advice.

Talk about your full service website!

Not to mention all the ladies over there discussing vacuums. Oh, come on, you knew I had to say it eventually.

Bren R.

It really sounds like the O/D isn't holding or the TCC is slipping, the fluid change will most often help a TCC issue, at least for awhile but not the O/D slippage. Good luck.

Didn't realize the Rodeo has an overdrive like my old trucks. I suppose I could try putting it in 3rd gear on the automatic shifter and take it out on the highway to see if I get any bump/nudge feeling.

Randy, out of curiousity, have you ever had any issues with your fuel lines freezing up/moisture in the lines....has this been happening only in colder weather?

I've been wanting to change the tranny fluid in my car, but just haven't gotten to it. More of a preventative thing for me (no noticeable problems). The biggest thing is that it can be really messy. The job itself isn't hard, but you need to be able to catch all of that fluid and it doesn't come out of a nice little hole like the oil does.

If you are having problems, you may need to take it in. Otherwise you could go through the task of doing it yourself, still have the problem, and then end up having a mechanic drain it again in their activities...

I just really felt like pulling that out of context.

That is all.

I've done a few tranny fluid and filter changes and they can be messy. No so much hard but a pita imo. I take my personal vehicles to the shop for the service. For 80 bux or so it's not worth the hassle to do it myself.

thanks guys, This vehicle has been rock solid in the cold Iowa winters, have replaced the battery a few times, never had problems starting. I was wondering about the cold freezing the gas lines also, but didn't think it would only affect speeds above 55 or so...

I may just take it in, I have a guy that has been pretty reasonable on other things in the past, 1/2 price compared to the dang dealers.

Hey, the worst it could be is a transmission rebuild!

Oh wait...

Good luck, Randy!

Can you leave it indoors somewhere overnight to eliminate the possibility of water in the lines? at higher speeds, your obviously drawing more fuel through the lines, so if there IS anything in the lines it could interfere with the flow. If you could eliminate that fact...it has been colder this winter I think.

140,000 miles?? Ya, you're past due Randy. I change mine at 30,000, but I'm anal about fluid changes. 60,000 is probably just fine, but 140,00 is way too long (in my opinion). I'd run it to a shop and have them do as Jay mentioned. Have them change the pumpkin fluid while they have it on the rack. Fluids also contain cleaning agents. It's pretty important to stay on top of that. The bands start slipping after they get gummed up. The Servo starts acting up as well. I hate working on auto trainies. They are a pain in the but...

If you do take it to a shop, make sure they don't sell you on a straight flush. They need to drop the pan and change the filter.

Adrian, it does sit in our garage all the time, but it is not heated. I would think at 55mph your drawing less gas, less rpm's and your in the D gear, compared to when your accelerating faster in 1, 2, 3, etc. at higher rpms's? I could be wrong. I can tell you when I step on it, the V6 has plenty of ummmf, and it appears to shift down and has no problem, just at cruise speeds. I think the problem is the tranny or rear end, not sure...

Sounds like it would be messy, heck sometimes when I change the oil I'm messy. I'll probably run it to my mechanic friend, it treats me right..

Frozen fuel lines, is a bit of a stretch, the higher fuel pressure pretty much alleviates any issues, unlike carbs with only suction drawing the fuel up the lines. Just in case their could be some moisture in the line you can try some gas line antifreeze just make sure it is fuel injector safe, the old stuff used to eat the o-rings on the fuel injectors etc., on that note a fuel injector clean might also be wise, as they can get gummed up and dirty over the years causing some surging as well.

Didn't get a chance to check the fluid levels/color this morning but did drive it into work. Around 55mph cruising speed, light pressure on the gas peddle (I'm not flooring it) is when you feel it, especially up hills. I think I even felt a little ruffnous (?) or it didn't seem as smooth at the D gear. The Rodeo is a 4x4 vehicle v6 and has L, 1, 2, D Automatic transmission. I'll call my mechanic today to see what he charges to drop the pan, drain everything, replace the filter, etc...I tried tapping the break quickly, but I don't think that helped...

Today it is supposed to hit 55F (crazy for early February in Iowa), so anything that would be frozen in your vehicle should melt today if left out in the sun.

I have never understood why people change fluids without installing a new filter, I've seen guys do oil changes and re-use the old filter. If me or anybody else is going to change any fluids anywhere on my vehicle that involves a filter, the old filter is coming out and a new one will be going back in regardless of the mileage.

I take that question mark to be a cry for help. The word you're looking for is roughness.

thanks spellingbot

It it funny when I know I'm spelling something wrong, but am to lazy to run a spell check.

The first thing I would do, and it would cost next to nothing, is run a couple of full tanks of gas through with a good fuel system cleaner just to see if there's any noticeable difference. Secondly, I would change the trans fluid/filter because you've got quite a bit of mileage on it, so you should do that anyway.
Your last post, Randy, reminded me of a '97 Chev S10 I used to own. Whenever I used to drive up the hills north of me, the truck would start 'chugging' and lose power, even if I floored it, and the engine light would come on. It only seemed to do it when the engine was loaded, like going up a hill, but not on level roads. I traded it in before confirming any problem, but I'm sure it was a bad sensor which caused it(fuel/oxygen).
Can you feel anything through the accelerator pedal? does it feel like the engine is faltering or is the engine feeling/sounding consistant while it makes the 'ruffnous'.

Adrian it did that because it was a Chevy, they all do that.

I never spell anything rong.

I have a 2001 Silverado now, I won't even tell you about the brakes...ABS constantly a problem. Had the problem "fixed" 3 times (twice as a recall, 3rd time Chev refused to pay for it). Basically a poorly designed ABS sensor in the front wheel hubs that malfunction, creating longer stopping distances even on dry pavement. There are numerous complaints/accidents on the 'net about this...I had several close calls in parking lots, at traffic lights, pulling into my driveway but worst of all I almost couldn't stop in a gas station one time and nearly pinned a woman to the back of her car.

Wow, that's not good.

My brother picked up an 05 Silverado, guess what he just had "fixed"....?

My father in law has the same problem, same truck.

I have a 00 Chevy S10 that I've been fighting with the "Passlock" system. There's been numerous accounts of folks having the same problem and no action from GM to make things right. My brother just called me and asked if I knew what "Passlock" was. It's hard to think that the same problems keep cropping up with no proper response from GM.

Hence GMs predicament....

I really wanted to "buy American" when I replaced my van this past Fall, but the Dodge/Chrysler just wasn't in the same category as the Honda in terms of build quality/design. At least the Honda is built in the U.S....

What I couldn't figure out was that Gm/Chev kept reinstalling the same defective part. When my brother had his ABS fail on his '05, I figured GM is still using the same design on their sensors (mine's '01)and I should add that my brother had to pay for his repairs(not warrantied or recalled as it should have been). This is, to me, a serious safety issue that should have been fixed permanently/redesigned years ago when problems first came to light.

I have never liked ABS and wish it was still optional on the vehicles I bought recently so I could have opted out.

Adrian, I had been thinking this, too. PCV valve, gunky throttle-body, etc.

Randy, when you start noticing the symptoms, can you put it in neutral, rev the engine and see what happens? I had a somewhat similar problem with our Ford Windstar that turned out to be an oxygen sensor. Obviously, if the engine revs freely from idle to redline, that is not the problem, but it might be worth checking.

PCV valve, mmmmm possibly, unlikely, it would show up at idle speeds more than cruising speed as would a gunky throttle body.

I checked out a couple of sources for similar complaints with his Isuzu, the most common for driveability issue(not a surging issue though) has been a corroded Engine Coolant Temperature sensor wire, the fun part is the sensor and subsequent wiring are under the intake plenum. I can remember doing one a number of years ago, I remember thinking the engineers were out to lunch the day they decided to put this sensor under the plenum. I did see a few complaints of surging, hesitations, etc., unfortunately no fixes were posted, but I have seen some unhappy owners having to rebuild their transmissons at 80,000 - 100,000 miles, which in my books isn't that bad anyway, well 80,000 is a little short but 100K(although most do go well beyond now adays) is what most cars are designed to live to, anything beyond that should be looked upon as gravy. Of course if most of the driving is highway the the mileage will be increased substanially before breakdown.

The light throttle at cruising speeds causing the surge is a pretty good indicator that the torque converter is hunting or your OD trannie band is slipping. If the truck was older, it could be the vacuum module for torque converter lock up. I think they went electronic in the late 80’s, early 90’s and have been pretty fool proof.

But…if it was torque converter related, you would not feel as if the wind was pushing the rig back. The engine RMP would pick up to compensate and you’d notice that. I can’t help but think this is your OD band slipping.

Can you actually hear the engine hesitate, cough, sputter, miss or anything unusual? If you could verify if it is the engine or not, that would help. Low RPM cruising speed surges can be caused by a multitude of different thing. Vacuum leaks come to my mind first. It’s not the PCV, but if you want to check, pull it and look for milky goo (emulsified oil) in the valve cover. You can usually see it on the PCV…

It’s not your fuel line. You’d be missing and sputtering all the time, right before the engine died completely.

I can remember replacing the TCC switch on the old THM200's from the late 80s and early 90s, it was always the first thing to disconnect when the complaint was surging at highway speeds.

I have a 2000 Silverado Z71 never had a single problem.

Knock on wood!

Mine's a 2001 Silverado Z71. Every two to three yrs the ABS sensors screw up. There was a recall on this about 5 years ago which I got done twice...the first time I paid myself about $400.00 then was reimbursed by GM about a yr later. The problem happened again 2 yrs later and GM paid for it(recall). The third time it happened about two years ago they refused to fix it, so they were in fact making me pay for their bad sensor design. Other than that, the trucks been reasonably reliable(recently the electric window gear disintegrated on the drivers side). I feel they should have redesigned the sensor, as my brother had the same experience with his '05(Sierra not Silverado as posted earlier). I think the sensors get corrosion from the salt in the winter and foul up, I'm not sure, but it can lead to a very dangerous situation.

The sensor was most likely slightly redesigned thus the recall, unfortunately due to the operating environment there isn't much they can do, except IMO, shut the ABS off even at low speeds like they used to be. In the beginning the ABS was not active unless vehicle speed was over 35MPH, IIRC, that was a while ago.

Jay, I've owned nothing but GM products and always will, you take care of any vehicle and it will last for a long time...my wife mixes it up a bit with the Rodeo and her Honda Pilot.

Adrian, 77,000 miles on my Silverado and never had a problem.

Back to the fluid, checked it when I got home, rubbed some off the dip stick onto some white paper towels, kind of a light/clear redish/pink color. Forgot to smell it...

You've had better luck than me:

One transmission, due to input shaft splines shearing.10,000kms warranty

Front wheel bearings/hubs both sides at 85,000kms $$$

3 times issues with ABS, twice warranty, paid last time but is still an issue now

Has had the well known Chev V8 "piston slap" sound on startup. Not so much an issue as irritating.


Driver's side elect. window gear shattered recently (motor works still)

I drive about half city/hiway and always change oil regularly and don't use the truck off road or abuse it. I used to trailer a fairly light boat for a couple of years(about 3000 lbs comb boat/trailer) Total mileage now is about 160,000 kilomtrs.

I won't say I'm unhappy with the truck, am I totally satisfied? no. Out of the repairs that it needed, I was most pissed about the front bearings/hubs($1400)....they should last the life of the truck imo.

That's like taking a shower and putting on the previous day's underwear.

Bren R.

Hey, when you're a college student and haven't done the laundry for a couple weeks ... certain compromises must be made.

Yes, laundry before food.

There's a reason I never put on the Freshman Fifteen.

Bren R.

I think I actually considered inventing moebius underwear at one point...

What I meant by my knock on wood comment was you may have jinxed yourself.

You can take care of any product and if there are manufacturing defects it will still break down. Even when there are no defects, if it is used hard or outright abused, it can and will breakdown at some point. I get to see it all first hand, owners have come in, had all the regular maintenance done and they still end up with blown motors, water pumps failing at will, etc.

The Trans fluid by your description sounds like it is still clean and OK, not burnt, if it was burnt it would have been brownish in color.

One reason might be because you have a fairly new filter but water in your system. Of course, not everybody drives in water up to their headlights.

Sirquack, I've been turning wrenches for a long damn time, and about 13 years were spent almost exclusively with Isuzu at a couple of dealers. I can tell you that if the TCC test, accurately described by Jakewash, doesn't get you any results, I'd pay some attention to the O2 sensor. It's located where the left and right bank exhaust pipes come together, and if I had to bet, there's probably a lot of oil on the connector, probably leaking from the valve cover gaskets. Unplug it and clean that connection with some spray contact cleaner, let it drip dry, or blow it out with compressed air. CRC makes a spray called Lectra-motive, works well. Also, if you had any top end engine work done recently, check some ECM grounds to make sure they're tight. You can see one on the front of the intake plenum, secured by a 6mm bolt that points toward the rear of the vehicle. There's also one behind the coil pack, secured by one of the big fasteners holding down the plenum.
I'd also recommend changing that O2 sensor if it's never been done.
Oh yeah, it wouldn't hurt to do a trans service, but it's not as easy as most, because the exhaust is in the way. Also, the gaskets are paper, and they have been holding hands with the trans case for a long time, so you have a heck of a date with a scraper if you do it yourself. There's 2 pans, the filter is beneath the larger of the two. I'd definitely pull the pan down first. If you haven't serviced your trans in a long time, then just flush it, some debris can end up in the valve body and give you some real shifting issues.
Anything I can do to help, let me know. I'll be standing here, holding my beer.

Wow! Hogie is today's MVP!!

(go ahead and get another beer; that one must be flat and warm by now)