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How to make an auto transmission last longer?

12-17-2006, 07:33 AM
The more that I use my trooper the more that I like it and the more I want to keep it. Most of my past cars I have been able to be get between 250,000 to 300,000 miles before having any internal engine or transmission problems. The key to reducing problems is regular maintenace and sometimes changing or fixing OEM design problems. For this thread I was wondering what type of fluid and filter will keep my trooper transmission running as long as possible. Also because I live in south Texas heat is my biggest problem. (Today it is in the 80s and it is almost Christmas.) I have already by passed the fluid lines to the radiator and added an after market cooler designed for a 1 ton truck. I am not a transmission guy so I do know anything about automatic transmission other than I have been told that heat can and will damage a transmission. I think that I have read that fluid temperatures over 240F is not good so it does not make sense living in the south to heat up my fluid by running it through the radiator. If I install a temperature guage to look at fluid temperature what is the best range to operate in? How often is best to change the fluid? If I spend a week in the desert off roading (Big Bend, Moab) do I need to do something special?

Ramblin Fever
12-17-2006, 11:16 AM

I too have the automatic - have had 2 Rodeo's, both with the same transmission I'm assuming you have, 4L30-E GM transmission.

Both of my Rodeo's have been/lived all over this country; in the desert southwest in temps upwards of 120F; to south of the mason dixen; north to Wyoming/Montana, Oregon, Washington, up and over the continental divide in the Colorado Rockies more times then I can remember.

More times then not, these two Rodeo's were pulling a 4,000#, 18' boat, luggage carriers loaded with 200# or so pounds of gear and generally 4-5 people in the truck along with a couple dogs.

These trucks also saw a lot of 4x4 adventures - down into riverbeds, mineshafts, sandpits (of the desert), and have even had their share of exploring edges of the many lakes we've been too.

Both Rodeo's have made it over 160k so far, with the original transmission; I traded the older '91 Rodeo for a dodge diesel that now takes over much of the towing responsibility; but the '97 Rodeo that we still have still leads a fairly aggressive life.

On both Rodeo's I had also added plenty of aftermarket weight, so even with empty loads, these trucks were quite heavy on their own feet.

We have done quite fine with changing the fluid EVERY 25-30k miles with complete fluid swap. If you do a partial fluid swap, do it every 15k miles. I don't think the type of fluid, other then what the manual calls for, is as important as doing the actual service.

The cooling system is VERY important as well, not just for the transmission, but the engine is all aluminum as well - so it's just as critical for it too; we change our antifreeze & flush every year. Thermostats get replaced every 50k or so.

And both Rodeo's - at the time of their 9-10yrs of age, got new Radiators and ALL new hoses.

With this routine, we have never once had an overheating issue with either the engine or transmission; nor did we ever install an aftermarket transmission cooler. Our rule of thumb has paid off in terms of driving the vehicle nicely, we have NEVER gunned the throttle on either truck, and we're not afraid to shift down our gears to give the tranny that extra help.

In other words, even without towing, we're the last person/truck to leave the light after it's turned green.

BTW - I am the original owner on both trucks, so their history/maintenance started from the beginning. I TRULY believe this makes the difference in longetivity on these transmissions, is making sure it's ALWAYS had service.

For your type of lifestyle, if you can do partial fluid swaps yourself, go for every 15k miles; if you do complete swaps (done by a machine), go for every 25k miles, and I'd change the filter every 40-60k or so.

12-17-2006, 02:07 PM it does not make sense heat up my fluid by running it through the radiator. ...

the trans fluid is not run through the radiator per se. it is run through part of that assembly reserved to cool the trans fluid only, the same way the main part of the radiator is used to cool the coolant, i.e. by heat transfer, which it seems to do quite efficiently, though any number of people seem to add 'external' trans coolers (radiators), especially those who do alot of towing and/or steep-grade mountain driving.

as to the temperature, i think it depends on where you locate the sensor. the two spots i've seen are either the inlet or outlet of the cooler (depending on whether you want to know how hot it's gotten or how hot after it's cooled), and also in a tapped hole in the trans itself which is the same size as the aftermarket trans temp gauge pickup sensors.


12-19-2006, 05:03 AM
Mr Fever when you changed all of your hoses did you also change the front and rear intake manifold cooling hoses and if you did, how did you do it? I have been hoping someone would tell me the secert of how to change thoses hoses.

Thanks for the great advice. It is always a great help to repeat the sucess of others verses reinventing the wheel.

12-21-2006, 10:42 AM
Hi, my experience with auto transmission is to change the trans fluid to a full synthetic and change the filter and fluid at least to the factory mileage recommendations. Synthetics are proven to hold up better to heat and provide better heat transferrance capabilty, which means that the trans runs cooler than with conventional fluid and can transfer heat better in the process. Another plus is that the synthetics tolerate higher temps without the burning and breakdown that conventional oils may incur. That does not mean they won't break down, but they give a greater range for consistent performance. I don't know from personal experience, but trans flushing does not sound like a great idea in a trans that has a lot of miles on it. Flushing also requires a lot of care to be exercised that non professionals might not bother with.
One owners opinion.

01-02-2007, 10:50 PM
what ive seen in auto transmissions is damage from water maybee just moisture keep a close eye on this it will burn up your drums and stuff and it will apear to be done by heat. Full flushing wise do it if you have the proper machine and expierience so you basically probably cant afford to do this ie 2000 sounds about the right cost so just take it to the shop. personnaly dont listen to factory recamended fluid entervals especially if you have fun with your car i dont remember right now but ask a technician or search for it on the boards or net for the recamended miles also find info on band adjustment or you might find yourself missing 2nd gear and burning up a drum. also pay attention to how hard it shifts if it hits harder you are being mean to your tranny and you should check your valve body.

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