Automatic transmission oil change

I have always heard that thing about how changing transmission oil on a high mileage automatic transmission can cause it not to work. is this an urban myth or truth? I am picking up a '95 F-150 with 200k miles on it tonight.

As long as you install a new filter, I don't see it being a problem. The story started from someone doing a flush without changing the filter. Or the transmission was about to die anyway.

I have fixed several automatics that all they needed was fresh fluid and a filter.

+1 for what iceracer said. And look at it this way, if the box gives out after a proper fluid change, it was probably on the very brink of failure and could have happened in the middle of nowhere.

The theory is plausible. Deteriorating transmissions could basically be using the gunk to help it function without deteriorating more. If you clean out what helps hold it together, you'll kill it faster. So it's plausible only with a transmission that is already on it's way out.

What I've heard is that if there are a lot of miles (120k+) on an auto transmission and the fluid has never been changed, just leave it alone if it isn't giving you any problems. If it starts to act up, then a fluid change might help, so do that because you've got nothing to lose -- either the change will solve the problem, or you needed to go ahead and do the five speed swap anyway.

There is some truth to it. The new fluid tends to wash away everything the old fluid was holding for the bearings and clutches. It is similar to cleaning a surface of oil and not putting any back on it for lubrication.

Plus at the mileage listed, waste of money. It is on borrowed time whether you do it or not. It is going to cost you the same when it breaks.

What is the transmission in a '95 F150 with a 5.8 and towing package?

look at the shift indicator.

belteshazzar wrote: look at the shift indicator.

Nope. OD button on shifter. If it is there, E4OD, if not, AODE/4R70. Or just look under the truck for the E4OD's 2' long trans pan.

How long do either of those transmissions last?

Edit also just noticed I am a Megadork...

Double edit: also it is AODE

93EXCivic wrote: How long do either of those transmissions last? Double edit: also it is AODE

Normal GRM answer: "It depends." I have the E4OD in my PSD F250 rolling 213k on the factory build including the 1st owners 5th travel trailer hauling. But others can't get 50k out of them even if they buy the $4k BTS rebuild.

Aode's don't have the capacity a E4OD has for towing.

93EXCivic wrote: What is the transmission in a '95 F150 with a 5.8 and towing package?

Driver side door panel has the transmission code on it. Is it a U? If it's U, you have a 4R70W transmission.

Ranger50 wrote:

93EXCivic wrote: How long do either of those transmissions last? Double edit: also it is AODE

Normal GRM answer: "It depends." I have the E4OD in my PSD F250 rolling 213k on the factory build including the 1st owners 5th travel trailer hauling. But others can't get 50k out of them even if they buy the $4k BTS rebuild. Aode's don't have the capacity a E4OD has for towing.

Damn $4k for a rebuilt one. How much is a E40D and how hard is it to swap if/ when the current transmission goes? I am buying the truck from a fellow GRM member so it is probably better taken care of then your standard F150.

93EXCivic wrote:

Ranger50 wrote:

93EXCivic wrote: How long do either of those transmissions last? Double edit: also it is AODE

Normal GRM answer: "It depends." I have the E4OD in my PSD F250 rolling 213k on the factory build including the 1st owners 5th travel trailer hauling. But others can't get 50k out of them even if they buy the $4k BTS rebuild. Aode's don't have the capacity a E4OD has for towing.

Damn $4k for a rebuilt one. How much is a E40D and how hard is it to swap if/ when the current transmission goes? I am buying the truck from a fellow GRM member so it is probably better taken care of then your standard F150.

Paid $600 for my rebuilt 4R70W and by the feel of it, it's not stock. It allows for a higher revv before shifting when being floored.

In reply to N Sperlo:

They probably put in either a Sonnax SureCure kit or a Shift kit from TransGo. And if that was a bench job, ouch.

Is the dipstick covered in little flakes of metal? If not, you should be ok doing a fluid excahnge.

If the fluid looks healthy(red, doesn't smell burnt) then you can get away with just dropping the pan, changing the filter and topping off.

The theory is that all the worn friction material is suspended in the fluid. If you change the fluid, all the friction material is gone. Not sure how much truth there is to it. I've never had one fail after a fluid service, but plenty of bad transmissions that didn't get any better.

I have also heard to just drain and refill, not flush. for the aforementioned reasons of not dislodging debris that will get caught up somewhere else in the trans and cause an issue.

I just did a drain and refill on my Toyolla's transmission. Didn't bother dropping the pan and changing the filter because the fluid looked perfect. (The previous owner was meticulous about maintenance.) So far so good.

Also, why don't all automatic transmissions have drainplugs? That made it SO easy.

Sky_Render wrote: Also, why don't all automatic transmissions have drainplugs? That made it SO easy.

How many times are you going to change it, compared to the engine? Then enter the bean counters, who aren't engineers or people who fix them....

Cone_Junky wrote: The theory is that all the worn friction material is suspended in the fluid. If you change the fluid, all the friction material is gone. Not sure how much truth there is to it. I've never had one fail after a fluid service, but plenty of bad transmissions that didn't get any better.

This. I have seen it first hand. A guy I worked with had an old Lumina that had a slight transmission leak and a weak transmission. If he topped it off with new fluid when it was low, it would slip like crazy and almost totally lose reverse. If he topped it off with nasty old fluid out of an old transmission (we worked at a salvage yard) it would drive fine. I have also seen vehicles that were slipping not pull after a fluid and filter change, but after it's slipping you're not losing anything by trying, because I've also seen them work a lot better after the fluid change.

Ranger50 wrote:

Sky_Render wrote: Also, why don't all automatic transmissions have drainplugs? That made it SO easy.

How many times are you going to change it, compared to the engine? Then enter the bean counters, who aren't engineers or people who fix them....

Not only that, but if you didn't have to drop the pan to change to fluid, how many people would change the filters? Sure, it would be nice if you could drain them before dropping the pan, and it would also be nice if more of them had spin on filters so you did have to drop the freaking pan, but I don't expect that to happen anytime soon.

Saturn S-Series have spin on filters, Some Subies do too.

Ranger50 wrote: In reply to N Sperlo: They probably put in either a Sonnax SureCure kit or a Shift kit from TransGo. And if that was a bench job, ouch.

No clue. I'm not a fan of modifying auto transmissions. Hell I'm not a fan of auto transmissions at all, but it sure tows good. I actually cracked the first transmission in half. The second has been doing well, but if it gives me any more problems, I've got a friend that will rebuild it properly. When the drive shaft blew off, everything looked fine. Except for the extension housing. That was broke, but I replaced it.

As someone who ran transmission repair shops for 13 years, I'll offer this.

The fluid change theory is partly myth and partly true. If you have a transmission that shifts properly and isn't slipping, 9 times out of 10 its fine to change the fluid/filter. If you have a transmission with problems, 5 times out of 10 changing the fluid will do more harm than good.

Transmission fluid (contrary to popular belief) is not loaded with detergents. It has very few detergents compared to motor oil. However - it still has detergent properties... that is to say that it dissolves things. If you have a transmission on its last legs and you change the fluid, it can accelerate the dissolution of clutch material leaving you with no clutch material.

Think of clutch material and fluid like rust and sandpaper. You can handle rust in one of two ways; periodically coat the steel with something that prevents it (which is equivalent to scheduled fluid changes) or you can wait and sand the rust off when it gets bad. If you wait long enough, the rust will have penetrated a significant amount of the steel and sanding it will make the remaining steel very thin.

In the same way, clutch material gets burnt. If you continually change the fluid, the burnt material will dissolve gradually and safely. If you don't change the fluid, more and more material gets burnt deeper and deeper into the surface. Changing the fluid at long intervals means that the potential for more clutch material to be dissolved. Overall, that isn't a bad thing. The clutches still degrade at a relatively constant rate and the fluid still dissolves it.

There are inherent problems with long change intervals of course.... the fluid becomes less able to lubricate, the filter becomes clogged, etc. If you let it go long enough, the fluid becomes saturated and can no longer dissolve the stuff its given. At that point the nasty stuff starts getting deposited in the corners of the valve body, wedging itself between check balls and plates, eating away at servo seals, and plugging solenoids.

Here is what I used to do at the shop. If you pull the pan and find burnt nasty fluid with a coated magnet, you should be fine. If you find that the magnet looks like a pincushion, or the bottom of the pan has significant black precipitant in it, its best to put the pan back on with the original fluid. This was biased toward protecting our butts. We were overly cautious so we didn't have pissed off customers.

In your own vehicle, I would change it MULTIPLE times. If the transmission is on its last legs, it will fail... but it would have failed in another 2000 miles anyway. Not changing it is suicide. It will just get worse. If you change it and things are fine, you did a good thing. If you change it and it fails, it would have failed anyway. If you don't change it, you have ensured that it WILL fail sooner than it needed to.

Most E4ODs and some AODEs have drain plugs on the torque converter. Pull the pan, pull the plug on the TC, and let it drain. Then start it up and run it for 10 seconds with the pan off. That won't get it all, but its a start. Replace the filter and gasket, refill, and drive.