Transmission fluid change

[Bj]

Hi everyone, I recently bought a a 99 Ford ranger but don't know much about it's background, i have been thinking about changing the transmission fluid, its kind of a brown color but doesn't smell burnt, I have been told by several people that if I change the fluid and filter it will ruin the transmission if it hasn't been done before, I like the truck and plan on keeping it, is it safe to change the fluid?

 

[JukkaK]

How many miles on the truck? If your automatic transmission works good just change the fluid and the filter. It's when people already start having problems with their transmission when they usually change the fluid and it won't help in that point anymore.

When people tell you that changing the fluid will ruin your transmission they believe that the new fluid will get some dirt moving in the transmission and it will cause problems. I haven't seen that ever happening. That might be the case if you are dealing with 20 years old dirty fluids but even then it's not guaranteed that it will happen.

 

[Bj]

It has 177,000 miles on it, it seems to shift good

 

[adsm08]

Jukkak is spot on. The relationship between flush and destruction is a case of mistaken causality.

A lot of techs who don't know much about transmissions (I am included in this group) will get handed work orders for poor shifting, or some other fairly minor issue, recommend flushing the trans because new fluid cleans and lubricates better, and often poor shifting is a sign of something getting stuck in the valve body. The customer approves the flush thinking it is a fix-all kind of thing, rather than a "Well let's start by getting your basic maintenance up to date" thing. Then because the issue was more serious it actually breaks a little while later, after it seemed good. They then assume, because all customers think this way, that the flush must have damaged something inside the trans. So they go tell their idiot brother in law, who tells his idiot co-workers, and pretty soon the whole world thinks that regular maintenance, especially if it was overdue, is going to break their car.


The truth of the matter is if you change your fluid and the trans breaks right away it was on borrowed time already because the dirt was all that was holding the guts together.

 

[91stranger]

I disagree. I believe that you should change your fluid IF you are under 100,000 miles. If you are over 100,000 miles then just leave it alone. However, if you are over 100,000 miles then you should use the syphon technique rather than dropping the pan. I'd say if it is shifting good then leave it be. If you are having issues then a simple fluid change will not fix it anything.

 

[black_demon69]

I am with adsm and Jukka on this one


Just my 2 cents

 

[Dirtman]

I'd say if it is shifting good then leave it be. If you are having issues then a simple fluid change will not fix it anything.

That's like saying you shouldn't change your engine oil if your engine is still running good?

Yes, change the fluid. In fact when I service a trans with unknown history I'll do 3 pan fluid changes (dropping the pan only changes 30-40% of the fluid) over the course of a month or two in order to slowly change ALL the fluid. After that stick with doing regular service (pan drop & filter change) every third engine oil change or 30k.

I don't like flushing machines on older transmissions, if you want to do a total flush use the cooler line and bucket method. I still feel consecutive pan drops, although more labor and time consuming is a gentler and more effective way to clean out an older transmission.

 

[adsm08]

I disagree. I believe that you should change your fluid IF you are under 100,000 miles. If you are over 100,000 miles then just leave it alone. However, if you are over 100,000 miles then you should use the syphon technique rather than dropping the pan. I'd say if it is shifting good then leave it be. If you are having issues then a simple fluid change will not fix it anything.

I did an inline flush on my sister's Volvo with over 200K on the clock already, pretty sure it was the original fluid. It looked like coffee.

That trans took her another 50K miles between here and Nashville before a water main exploded right under the car and ruined the inside.

She sold it to someone she knew who had the time and gumption to repair the interior and when she left Nashville two years (four years after the flush I did) later that car was still running around.

 

[Bj]

Thanks for the input, I think I will go ahead and change the fluid and filter

 

[91stranger]

That's like saying you shouldn't change your engine oil if your engine is still running good?

Yes, change the fluid. In fact when I service a trans with unknown history I'll do 3 pan fluid changes (dropping the pan only changes 30-40% of the fluid) over the course of a month or two in order to slowly change ALL the fluid. After that stick with doing regular service (pan drop & filter change) every third engine oil change or 30k.

I don't like flushing machines on older transmissions, if you want to do a total flush use the cooler line and bucket method. I still feel consecutive pan drops, although more labor and time consuming is a gentler and more effective way to clean out an older transmission.

If it is over 100k and the fluid is off color then I wouldn't touch it. Transmissions are a sealed system so if it is off color then that means something bad is happening inside the transmission. Once you change the fluid you are essentially cleaning it which could break up deposits or change the pressure inside the transmission which could cause shifting issues or just ruin the transmission completely. You all can say what you will. I am just telling you what any service shop will tell you. If you want your trans fluid changed it has to be under 100k or else they don't touch it because they don't want their name on a bad transmission. There's a reason for that don't ya think.

 

[Craig0320]

91stranger Just because it is off color does not always mean something bad is happening inside the transmission. The fluid can only stay a light red color for so long under so many heating and cooling cycles through the fluid life. If it is getting to be a maroon or dark red color then it is time to change the fluid and filter if someone lets it go that long. I change mine every 30k no matter what on my vehicles. I have changed the fluid and filter in numerous vehicles from 100-200k that were brownish in color that I know for a fact have never been changed before and never had a problem afterwards. Power flushing with the machine to move contaminants out of the system is the big no no on higher mileage transmissions that have not been taken care of. I have heard of a few that had problems afterwards, but just a few. Just my life experiences.

 

[Bronson]

So I googled a bit and found some basic maintenance tips for trucks with 150k mileage, and automatic transmission/transaxle fluid and filter are right on the list.

Here's what happens at your 150000 mile checkup

MEMO: Gas engine; Up to 5.0 quarts of oil (4.0L)
Replace cabin air filter, if equipped
> Change automatic transmission/transaxle fluid and filter
Inspect automatic transmission fluid level (if equipped with underhood dipstick)
Replace fuel filter
Replace rear axle lubricant
Rotate and inspect tires; check wheel end play and turning noise
Change engine oil and replace oil filter (See Owners manual for time based oil change intervals)
Replace engine air filter
Inspect cooling system and hoses
Inspect complete exhaust system and heat shields
Inspect brake pads/shoes/rotors/drums, brake lines and hoses, and parking brake system
Inspect and lubricate all non-sealed steering linkage,ball joints,suspension joints,half and drive-shafts and u-joints
Perform multi-point inspection


P.S. Not sure if it was recommended by FORD, but this is what I've found online

 

[Dirtman]

If it is over 100k and the fluid is off color then I wouldn't touch it. Transmissions are a sealed system so if it is off color then that means something bad is happening inside the transmission. Once you change the fluid you are essentially cleaning it which could break up deposits or change the pressure inside the transmission which could cause shifting issues or just ruin the transmission completely. You all can say what you will. I am just telling you what any service shop will tell you. If you want your trans fluid changed it has to be under 100k or else they don't touch it because they don't want their name on a bad transmission. There's a reason for that don't ya think.

Transmission fluid changes color because it oxidizes over time... It is no indication of any problem with the transmission other than the fact that it needs to have the fluid changed.

 

[Craig0320]

Transmission fluid changes color because it oxidizes over time... It is no indication of any problem with the transmission other than the fact that it needs to have the fluid changed.

 

[Shran]

Transmissions are a sealed system so if it is off color then that means something bad is happening inside the transmission

Using this logic, I will never again change my engine oil, coolant, brake fluid, or power steering fluid.