Changing transmission fluid and filter

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Jul 17, 2002
Hey guys!! I am currently trying to decide whether or not to change my tranny fluid. I have a 1998 Chevrolet Monte Carlo in addition to a GMC Sonoma pickup. I bought the car back in November 2001 with 27,000 miles(approx.) on it. It is a four speed automatic with the 3.1 LV6 motor. My real question is why does the owner's manual suggest I not change the tranny fluid unless I operate the car in severe service?? Is the Schaeffer's tranny fluid a good product and what brand of tranny filter have you guys had good luck with? When I buy a vehicle I usually keep it for a long time so I'm not worried about cost. Any suggestions or advice would be appreciated.
Most people fall under the definition of severe service. I believe, it's more of a mix though. Example; If you do 1/2 city 1/2 highway and the severe engine oil interval is 3000, with the "normal" being 7500, then you are probably good for 5250 ((3000 / 2)+(7500 / 2). At least, that's how my oil change light would see it. Personally, I have trans fluid flushed every 50k. It's cheap insurance. Schaeffers is good fluid, one of the best. I just run OEM.
Despite what any manual may say, I like to change auto tranny fluid every two years at the very most, in some cars I have done it every year! It's cheap insurance, as auto trannies can cook that old fluid and getting fresh stuff in there will definitely prolong it's life.
You didn't say whether it is automatic or stick. I assume automatic. At the very least look at it and smell it. If it smells burnt or is dark, get it out. Personally I never go more than 20K between changes. When you change use good stuff, at least a Group II. I was with a mechanic the other day that was repairing a $90,000 Mercedes because the owner insisted on Type A fluid because it was 5 cents a quart cheaper than Group II Dexron III.
Thanks guys. I think I will have it changed pretty soon--still clear and doesn't smell burned but like you all said "cheap insurance." widman--I did list that it was an automatic.
If you are planning on changing every 30k, it probably does not matter, but keep in mind. Getting a fluid and filter change usually means only 1/2 of the fluid is changed. In the case of your Monte Carlo, it would mean 7 out of 13 qts. In the case of your truck, it would be 5 out of 11 qts total.
Flushing is good but be sure to get the filter changed also. When I got my car, I had the trans flushed, but they didn't have my filter in stock, so I've still got the original one on there. This fall I'll have just a simple pan drop done and have them put on a new filter and fresh fluid (at this point I don't need a full flush though)
I have used Amsoil synthetic in over 5 cars now, various makes from Chev., Nissan, Buick, Ford, Toyota, Isuzu all with excellent results. I try to change, even with synthetic, every 30,000 or so.
As Patman says, get them to change the filter too, but yes, flushing is always a good idea. Would you change the oil and the filter on your engine, and then pour 2 quarts of the used oil back in? Personally I've had great luck with OEM AC fluid in my GM applications. About 475000 miles in 4 vehicles with no transmission failures. I do believe in putting the biggest transmission cooler that will fit though also. A cool transmission is a happy one, and I'll pick cool and conventional over hot and synthetic anyday. I think that the use of synthetic transmission fluid is way overkill unless it is needed, ie; heavy towing with a marginal tranny. If you do go with a synthetic, I don't recommend Mobil 1 ATF. I'm a fan of Mobil 1, but their fluid in GM trannies works great in some, not so great others. [ August 09, 2002, 09:58 AM: Message edited by: VaderSS ]
My problem with flushing is that I feel the filter should be changed after the flush which, unfortunately, wastes more new fluid and is time consuming. Most shops will not do it. Replacing the filter before the flush does not appear to me to be reasonable as all the contaminants released during the flush will remain in the filter. I only do a drain and fill which is part of the reason I start early, around 30,000 with a new car and do it every 30,000. Fortunately most of mine have a plug so I do not have to drop the pan. Even so, after 110,000 on filter/screen (fluid drain and fill every 30000) in my Toyota the screen was clean and only the magnets had some wear metals on them. Heard some horror stories about flushing but I have never had it done. [ August 09, 2002, 11:04 AM: Message edited by: Spector ]
I don't really feel that a "flush" has any kind of cleaning effect. I guess it should really be called an exchange. But everyone knows what flush means... Personally, I don't mind wasting some fluid, but then I go to 50k anyway.
I have been watching this great site for a while and appreciate all the information. I have been doing my own maintenance for years, and have this to add regarding transmission maintenance: You can do your own flush/fluid exchange at home through the cooler lines. Just disconnect one and have a friend start the vehicle for 1 second to determine which way the fluid is flowing. Connect some clear plastic tubing from Home Depot to the out flow line and into a 5 gallon gas can and a funnel to the other end that goes into the cooler/tranny, or plug that line and fill through the dipstick tube. Have a friend start and stop the engine on command so you do not run the tranny dry as you pump out and add fluid ( it goes out faster than you can pour). You will be able to see the color change when it is all exchanged. I usually change the pan filter first. Recently I added an inline transmission filter from Magnefine (along with the extra cooler). It contains a magnet, filtering media and bypass and has been approved by Ford. They claim the pan filter does not need to be changed for 100,000 miles if the Magnefine filter is changed every 2 years or 24,000 miles. These filters have become popular with the Taurus forum members. You can check them out at then click on the Magnefine section. Check out their forum for more information. They are available for less (about $14.95)from
They claim the pan filter does not need to be changed for 100,000 miles if the Magnefine filter is changed every 2 years or 24,000 miles.
That's really not a big deal when you consider that most automakers have a 100k+ change interval on trannie servicing.
Liquidballbearing--I've read on the net, articles in newspapers, and heard from a number of people at work that there seems to be in the last 10 years or so, an increased number of tranmission failures in modern cars. Basically, it seems to stem from the increased power density in modern powertrains. This results in in an increased concentration of heat in the engine and transmission. So, people in the know about the subject all seem to agree that it is wise to install an additional ATF cooler to reduce/eliminate this number one cause of transmission failures. Most likey, your transmission maintenance money is best spent on an ATF cooler, rather than more fluid changes. Last week I installed one on my 2000 Honda Odessey. I spoke at length to the Service Manager at a nearby dealership. He said that although the Odessey tranny is a good one, installing an ATF cooler is a good idea, for the reason I stated above. Hopes this helps in your decision.
Thanks guys!! I just may install a tranny cooler. The car is in mint condition and now has only 35,000 or so miles so this would be a win/win situation in my opinion and from the great advice you fellas have given me. How hard is it to install a cooler?? I'm fairly mechanically inclined so I would like to do the work myself. I think I'll try the Schaeffer's tranny fluid even though I've got to drive 40+ miles to get it--I'm assuming the place that sells their oil also sells their ATF. If not I may go ahead and splurge on the Amsoil ATF which I can buy at the Napa beside my house. Thanks again--this forum is great.
Clutchless, Would you post the link to bulkparts, the one you listed, I can't get to work. Concerning the Magnefine filter, the Ford part number for this kit is #XC3Z-7B155-AA. It comes in a nice box with a Ford label, then open it and there in all it's glory is the Magnefine filter. The filter number only is XC3Z-7B155-BA, 3/8" inch in-line filter. A few items on this filter, If you get a new or rebuilt trans from Ford, this filter must be installed or the warranty is void. Should be done by Ford. Second, you need to install a new filter at every fluid change or 30K. I am not sure where the 20K came from unless it is different on various vehicles. Also, if you use a flushing machine to change your trans fluid you must remove the Magnefine filter first, and use a cheater hose to connect the two lines for flushing. This filter is directional. I see alot of people talk about adding coolers and filters to your transmissions. Don't forget to do a flow specification test after you are finished. You will have to get the spec's from the Dealer. On my truck it is 32 ounces in 15 seconds. If you read low, you may have a CBV (cooler bypass valve), make sure it is operating properly if you get a low reading, if it is operating normally, you may then have a restriction in your system. [ August 09, 2002, 10:54 PM: Message edited by: 59 Vetteman ]
Some local auto parts stores also have the Magnefine filter packaged under the ATP label. About $24. It's available in 5/16" & 3/8" sizes. They also work well on your power steering system. Ken
Originally posted by 59 Vetteman: Clutchless, Would you post the link to bulkparts, the one you listed, I can't get to work. ....
The period after com is the problem with the link. Ken
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