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Givin' a car a tuneup

adk said:
Many shade tree mechanics will change only a quart or two of the ATF if the transmission fluid is long overdue for changing. Then, a month or two later, they'll change another two quarts. The idea is that a full fluid swap will "shock" the transmission and cause it to fail, something that has many anecdotal examples on auto message boards. Does it work? Who knows.
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As sort of a counter to that, one of the common "shade tree" methods is to drop the pan, which typically only gets about half the fluid out anyway rather than draining the whole transmission.

Most shops now use the "flush" method where they connect the transmission cooler lines to a machine that flushes out the old fluid with fresh while also cycling through the different gears. If this is done right, I think that it uses about 1.5x the total transmission volume, but does actually change all the fluid.

There may be some validity to it "disturbing" things in the transmission, I think that's likely still due to a transmission that's long overdue for service and is on the way out. Being proactive with fluid changes(as I said, I try to do it every 30K miles, which is what the guy who designed the transmission in my car told me to do, although I'm not as on top of it as I should be) can prevent a lot of this.
 
Actually it really depends, If you buy a car used and say its 10 years old with 120k miles on it. If the service manual says to change it after a X amount of years/miles and there is no knowledge of it being done OR it never is done, the degradation of the transmission with the fluid inside of it can cause harm when changed. If it's never been changed, you can develop leaks in places you never had them before. Bottom line is if you buy a car used unless you have service history records or ask the previous owner if the fluid has been changed (assuming its even recommended) than you should not change it. If you are the 1st owner and you change the fluid as per the service manual than its perfectly fine to change.
for example. the Engine in my Daewoo (and the Aveo) state specifically in the owners manual that you DO NOT need to change the fluid if it's got a automatic transaxle however, If you have a Manual Transaxle you are suppose to change the fluid every 30k miles IIRC.
adk said:
Many shade tree mechanics will change only a quart or two of the ATF if the transmission fluid is long overdue for changing. Then, a month or two later, they'll change another two quarts. The idea is that a full fluid swap will "shock" the transmission and cause it to fail, something that has many anecdotal examples on auto message boards. Does it work? Who knows.
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bunnspecial said:
The 40,000 miles on my car since the last fluid change disagree with you(I'm overdue for another change)

The 80,000 miles my dad put on one of his past cars also disagree with you.

Changing fluids is NEVER a bad thing.

I suspect that many of these anecdotal "your transmission will fail if you change the fluid" stories come from people who already have a failing transmission and change the fluid as a last ditch attempt to try and salvage the transmission. Changing the probably actually bought them a few more months, but their transmission was on the way out with or without a fluid change.

Like any other fluid, transmission fluid degrades and it actually undergoes a lot of stress. Not only is it a lubricant, but it also is responsible for things like controlling the slip on the torque converter and the gear changes. With a lot of use, the addititive that control these things can degrade-look at a sample of transmission fluid that's been run for 100,000+ miles(particularly if those are in-town miles) and it will probably have the color of motor oil and smell like burnt toast. How on earth can it be good for your transmission to leave that in?
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There is one car in particular I know of that had an unsealed transmission where the manufacturer stepped in and said not to change the fluid since drastically it was causing greater issues. I amazing the design of the transmission didn't allow for adequate flushing.

I do agree some manufacturers do this to decrease cost of ownership estimates (in addition to 14k mile motor oil changes). The thing with "sealed transmissions" is that some mfg still reccomend changing it eventually, it just means there's no dipstick. My BMW has a lifetime sealed auto trans (lifetime = 100,000 miles :rolleyes:) but suggested I change the fluid at 80,000 (though not covered in the regular maintence program).

In most cases I would agree not changing the fluid is silly but I know of at least one exception with an unsealed where it was deemed risky. Given the relatively short average lifespan of the vehicle (older Rovers - lifespan generally is well below 150k due to other issues), it might not be a bad decision.
 
A.Goldberg said:
There is one car in particular I know of that had an unsealed transmission where the manufacturer stepped in and said not to change the fluid since drastically it was causing greater issues. I amazing the design of the transmission didn't allow for adequate flushing.

I do agree some manufacturers do this to decrease cost of ownership estimates (in addition to 14k mile motor oil changes). The thing with "sealed transmissions" is that some mfg still reccomend changing it eventually, it just means there's no dipstick. My BMW has a lifetime sealed auto trans (lifetime = 100,000 miles :rolleyes:) but suggested I change the fluid at 80,000 (though not covered in the regular maintence program).

In most cases I would agree not changing the fluid is silly but I know of at least one exception with an unsealed where it was deemed risky. Given the relatively short average lifespan of the vehicle (older Rovers - lifespan generally is well below 150k due to other issues), it might not be a bad decision.
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My Daewoo (And the Aveo) have "Sealed" transmission there is no dipstick. I assume that reason alone is why they say never to change it. It DOES however have a cap on it and a vent hose connected to said cap..... so you could physically ADD fluid and im sure you could drain it but with no dipstick you'd have no clue how much fluid to add
 
MatthewLTL said:
My Daewoo (And the Aveo) have "Sealed" transmission there is no dipstick. I assume that reason alone is why they say never to change it. It DOES however have a cap on it and a vent hose connected to said cap..... so you could physically ADD fluid and im sure you could drain it but with no dipstick you'd have no clue how much fluid to add
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"Sealed" is the norm these days. My transmission lacks a dipstick, but has two bolts on the side of the transmission. If you loosen the top bolt and fluid comes out, there's too much. If you loosen the lower one and fluid comes out, you have enough. Really, it's a brilliantly simple system except that it's a pain to get to it.

Most shops now do a flush rather than a change. Basically, they just hook up the transmission cooler lines to a pump that takes the fluid out while replenishing it with fresh. It's done while the engine is running, and the person doing the change will cycle through all the gears while the fluid is being exchanged. It uses about 125% of the total volume of transmission fluid. The whole thing is done at the normal operating pressure of the transmission, so there's no risk of "breaking" something as many fear. A drain and fill(as done when changing the oil) will only get about half the transmission fluid, while a flush gets everything.

It's honestly a better way to do it, although it requires that the shop invest in the equipment to do it. I have it done at the dealer. It's a $90 job(most of the cost is in the fluid) and takes about a half an hour.
 
MatthewLTL said:
My Daewoo (And the Aveo) have "Sealed" transmission there is no dipstick. I assume that reason alone is why they say never to change it. It DOES however have a cap on it and a vent hose connected to said cap..... so you could physically ADD fluid and im sure you could drain it but with no dipstick you'd have no clue how much fluid to add
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In many cases dipsticks are actually available (some cannot be left in like an oil dipstick), either to the dealers or aftermarket.
 
A.Goldberg said:
In many cases dipsticks are actually available (some cannot be left in like an oil dipstick), either to the dealers or aftermarket.
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I cannot find anything for a aftermarket dipstick, From what i have read however is that you can use the engine oil dipstick inside the filler cap of the tranny to check the levels. However as stated below, my manual specifically states you simply DONT change it, so i wont.
bunnspecial said:
"Sealed" is the norm these days. My transmission lacks a dipstick, but has two bolts on the side of the transmission. If you loosen the top bolt and fluid comes out, there's too much. If you loosen the lower one and fluid comes out, you have enough. Really, it's a brilliantly simple system except that it's a pain to get to it.

Most shops now do a flush rather than a change. Basically, they just hook up the transmission cooler lines to a pump that takes the fluid out while replenishing it with fresh. It's done while the engine is running, and the person doing the change will cycle through all the gears while the fluid is being exchanged. It uses about 125% of the total volume of transmission fluid. The whole thing is done at the normal operating pressure of the transmission, so there's no risk of "breaking" something as many fear. A drain and fill(as done when changing the oil) will only get about half the transmission fluid, while a flush gets everything.

It's honestly a better way to do it, although it requires that the shop invest in the equipment to do it. I have it done at the dealer. It's a $90 job(most of the cost is in the fluid) and takes about a half an hour.
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well, since the manual of my car specifically states that with the automatic transaxle there is no need to ever change the fluid, I will go by that and never change it.
 
MatthewLTL said:
I cannot find anything for a aftermarket dipstick, From what i have read however is that you can use the engine oil dipstick inside the filler cap of the tranny to check the levels. However as stated below, my manual specifically states you simply DONT change it, so i wont.


well, since the manual of my car specifically states that with the automatic transaxle there is no need to ever change the fluid, I will go by that and never change it.
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If your transmission can fully drain, you can just add as much fluid as it the required specification too. Sealed transmissions are not literally sealed, so it is possible to open them and repair them, in which case the fluid would have to be drained and refilled. There is a listing for every sealed transmission I've ever experienced.
 
A.Goldberg said:
If your transmission can fully drain, you can just add as much fluid as it the required specification too. Sealed transmissions are not literally sealed, so it is possible to open them and repair them, in which case the fluid would have to be drained and refilled. There is a listing for every sealed transmission I've ever experienced.
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I will check over my owner's manual service schedule and quote it tomorrow. But i am 99% sure it says you DO NOT service auto transmissions.
 
MatthewLTL said:
I will check over my owner's manual service schedule and quote it tomorrow. But i am 99% sure it says you DO NOT service auto transmissions.
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It probably says not to.

That way they reduce the listed cost of ownership of the car. That's why you'll also see cars with 8-15,000 mile oil change intervals. BMW comes with factory sealed transmissions, as the fluid is good for "the life" of the car. "The life" is considered 100,000 miles though, which is different than others interpretations.

Oil degrades with time, use, and exposure to air, humidity, and particulates. Unless there is a vast history of issues created by draining the fluid, it seems silly not to. Since Daewooo information is limited, I would check to see if your transmission is used in other cars (Aveo?) and see what others recommend. Then again, you don't have many miles do you?
 
A.Goldberg said:
It probably says not to.

That way they reduce the listed cost of ownership of the car. That's why you'll also see cars with 8-15,000 mile oil change intervals. BMW comes with factory sealed transmissions, as the fluid is good for "the life" of the car. "The life" is considered 100,000 miles though, which is different than others interpretations.

Oil degrades with time, use, and exposure to air, humidity, and particulates. Unless there is a vast history of issues created by draining the fluid, it seems silly not to. Since Daewooo information is limited, I would check to see if your transmission is used in other cars (Aveo?) and see what others recommend. Then again, you don't have many miles do you?
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45,300 roughly last time I looked.
 
A.Goldberg said:
It's probably unnecessary right now, especially considering all the other things on your fix-it list.
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True, Hell my car ran on the factory coolant (and still tested good btw) up until it blew the thermostat back in 2013. It's still running on 1 original factory tyre, Factory PS Fluid and up until the brakes blew in 2013 it ran on the factory brake fluid.

I will either have to PS System serviced with a fluid change and/or flush or ill just do it myself. I can ALMOST get at the CPS to change that myself if i could only get the damn timing belt cover off, I can get to the wire to disconnect the CPS but thats about it. Looks like i'd have to take the air box out to get at it though.
 
MatthewLTL said:
True, Hell my car ran on the factory coolant (and still tested good btw) up until it blew the thermostat back in 2013. It's still running on 1 original factory tyre, Factory PS Fluid and up until the brakes blew in 2013 it ran on the factory brake fluid.

I will either have to PS System serviced with a fluid change and/or flush or ill just do it myself. I can ALMOST get at the CPS to change that myself if i could only get the damn timing belt cover off, I can get to the wire to disconnect the CPS but thats about it. Looks like i'd have to take the air box out to get at it though.
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Brake fluid is hygroscopic, meaning it absorbs water.Water + steel brake lines = rust. Rust = leaking lines. It's generally recommended to be changed every ten years.

15 year old tires are a disaster waiting to happen. The shelf life is considered 5-7 years. Even if they're not worn, after exposure to air and UV light, the rubber quality will diminish. It might not be as big a problem if your car is garaged. If there is evidence of cracking, you have a problem. Tires falling apart while driving is not only dangerous for control reasons, but can also do serious damage to your car.
 
A.Goldberg said:
Brake fluid is hygroscopic, meaning it absorbs water.Water + steel brake lines = rust. Rust = leaking lines. It's generally recommended to be changed every ten years.

15 year old tires are a disaster waiting to happen. The shelf life is considered 5-7 years. Even if they're not worn, after exposure to air and UV light, the rubber quality will diminish. It might not be as big a problem if your car is garaged. If there is evidence of cracking, you have a problem. Tires falling apart while driving is not only dangerous for control reasons, but can also do serious damage to your car.
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the car spent 7 years of its life in a garage it spent 3 years of its life in a car port its spent the past 5 years parked in the driveway
 
A.Goldberg said:
Brake fluid is hygroscopic, meaning it absorbs water.Water + steel brake lines = rust. Rust = leaking lines. It's generally recommended to be changed every ten years.

15 year old tires are a disaster waiting to happen. The shelf life is considered 5-7 years. Even if they're not worn, after exposure to air and UV light, the rubber quality will diminish. It might not be as big a problem if your car is garaged. If there is evidence of cracking, you have a problem. Tires falling apart while driving is not only dangerous for control reasons, but can also do serious damage to your car.
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Very true. My dad had a nail in the tire on his MKZ(2010, about 25K on the clock). I pulled it for him and took it to a reputable locally-owned shop for a patch(or plug, more properly).

When we went to pick it up, the shop owner took us out and showed us the extent of dry rot on the inside of the sidewall. He said we would plug it, but strongly advised against it. Even though the car was five years old, the date code on them showed a December '08 manufacture date.

Needless to say, my dad went ahead and replaced all four.
 
bunnspecial said:
Very true. My dad had a nail in the tire on his MKZ(2010, about 25K on the clock). I pulled it for him and took it to a reputable locally-owned shop for a patch(or plug, more properly).

When we went to pick it up, the shop owner took us out and showed us the extent of dry rot on the inside of the sidewall. He said we would plug it, but strongly advised against it. Even though the car was five years old, the date code on them showed a December '08 manufacture date.

Needless to say, my dad went ahead and replaced all four.
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Amazingly, My 15yo tyre has no dry rot at all and it still holds air perfectly, I will need 3 new tyres soon anyway they are getting pretty worn.
 
A.Goldberg said:
The dry rot can be on the inside and not the outside, just FYI. Why 3?
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That's what happened on my dad's car-the tires looked perfect from the outside. The problem only showed up with the tire off the rim. All four held air very well(I don't recall him ever needing to fill one). I was shocked, but it was indeed very extensive on the inside and especially on the sidewall.
 
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