Transmission fluid change or flush?

[DanTMWTMP]

I'm due in for a 30k service. Two oilchanges ago (at approx 23k miles), I was told that my tranny fluid is getting a bit darker, and I should have it changed in my next next oil change. This advice was from the dealer mechanic. I currently have almost 32k miles, and have owned the car for 23 months.

I intend to go to the stealership to get the 30k service done. There are couple reasons why I'm doing this. One, I want this car to last as long as possible so I can keep it until it absolutely dies. Two, if my luck turns to awesome and I want to invest in a new car, then I can sell this car at the highest possible resale value at any given mileage (I have kept all service records thus far... which have been oil changes lol). Three, Preventive care.

Anyway, should I be worried about a transmission fluid change? I've heard conflicting reports of people doing a transmission flush. Some people suggested to do it every 30k. Others have said to do it every 50k. A couple others have mentioned to just do it every 100k miles. Still others have advised against a flush, and just changing the filter and doing a regular fluid change is just fine.

So, along w/ my 30k service, should I be requesting any service to the transmission? Should I actually go to a respected mechanic to do it for me instead?



EDIT: btw, a transmission flush/refill by the local mazda dealer here in SD costs $220 minimum (depending on what fluid is in it).
EDIT2: called a couple other mechanics. All quoted around the $220-230 range. haha. Looks like i'm headed to the dealer.

 

[chucky2]

For your first change in your car, you should get both a filter change and then a flush done. A flush will take out most of the old fluid in the transmission, rather than just 3-4 quarts.

The next 30k miles (and Yes, you should be doing this every 30k mi.), you can just do a flush, no filter change needed.

Couple of important things:

1.) Make sure they are using the correct fluid - don't assume it, confirm it. This means the actual correct fluid, not something close with an additive added to it. Example: If your car needs Mercon V, they should not be using a Mercon fluid with an additive to "bring it up" to Mercon V spec....they need to be using a straight out Mercon V rated fluid. Don't debate this with them: Either they use the correct fluid straight out, or, you just go someplace that can do the job correctly.

2.) You do not need any flush additives or after flush additives added. Just plain Mercon V fluid - if that's what your Mazda takes - is all you want in there. Using harsh solvents in the flush, or, after adds that Ford engineering (note: this does not include Darrel the trans change tech or Darrel the service writer) has not approved, is not needed, and may in fact harm your trans in the long run.

If they can do all these things correctly, then you should be all set.

One more thing: After they're done, you need to follow the proceedure in your manual for checking the transmission fluid. I've seen it multiple times where either the fluid is too low, or, too high after doing one of these flushes. Make sure you do this as running underfilled or overfilled is not good.

Chuck

 

[Zenmervolt]

A flush can be bad if the transmission is a high-mileage unit and has not had the fluid changed regularly. If the fluid has been changed regularly, then a flush is fine. Most modern automatics will last a good long time even without flushing the fluid, however I still tend to side with the flush/refill every 30,000 miles viewpoint. This cannot harm the transmission and will only serve to help keep it in shape for the longest possible amount of time. Dealer price on this should not be out of line with other service costs.

ZV

 

[Elstupido]

Do not flush a tranny with high mileage! Drain, refill and filter change. At that mileage, though a flush would be preferable

 

[StageLeft]

Others are echoing what I've heard. I have an '04 mpv with 68k on it with no transmission maint. I'm about to change out all the fluid and not do a flush, simply dump the fluid and put more in and then after it's run for a short while (days or something) do it again. I've heard that's decent in the face of a higher mileage transmission with no maintenance.

 

[fstime]

I wouldn't flush. Do a drain/re-fill about 3 times every 3.000 miles or so.

This should change a good percentage of the old oil.

 

[Juddog]

Originally posted by: BouZouki
I wouldn't flush. Do a drain/re-fill about 3 times every 3.000 miles or so.

This should change a good percentage of the old oil.

LOL wat?

 

[Elstupido]

A flush will change out all the oil in the torque converter that a normal drain won't. The old oil remains in the torque converter when not flushed.

Problem with flushing is it stirs up all the stuff that can make your tranny run normally after a lot of miles, and lead to failure.

 

[fstime]

Originally posted by: Juddog

Originally posted by: BouZouki
I wouldn't flush. Do a drain/re-fill about 3 times every 3.000 miles or so.

This should change a good percentage of the old oil.

LOL wat?

When do you a drain, only a small percentage of the total tranny oil comes out, say 3.5 quarts out of the total 8.5 quarts.

Because of this, you need to do the drain/refill method several times to replace a good percentage of the old oil with the new.

Drain/refill, repeat every 3,000 miles or so about 3 more times.

I have a calculator somewhere on my computer that shows how many times you need to do this to replace 100% of the fluid.


This method is safer than flushing the tranny which could cause something to to wrong, especially in a high mileage car.

 

[thomsbrain]

At your mileage, I would flush it.

 

[Juddog]

Originally posted by: BouZouki

Originally posted by: Juddog

Originally posted by: BouZouki
I wouldn't flush. Do a drain/re-fill about 3 times every 3.000 miles or so.

This should change a good percentage of the old oil.

LOL wat?

When do you a drain, only a small percentage of the total tranny oil comes out, say 3.5 quarts out of the total 8.5 quarts.

Because of this, you need to do the drain/refill method several times to replace a good percentage of the old oil with the new.

Drain/refill, repeat every 3,000 miles or so about 3 more times.

I have a calculator somewhere on my computer that shows how many times you need to do this to replace 100% of the fluid.


This method is safer than flushing the tranny which could cause something to to wrong, especially in a high mileage car.

Ahh the way it was phrased made it sound like he should be doing the drain / fill 3 times every 3,000 miles.... which would end up being a very large amount of fluid (in other words, 9 times after 9,000 miles, etc.).

 

[Pacfanweb]

The "flushing loosens up grime and causes failures" is pretty much a myth. Every mechanic I know (including myself) has told people that, but nobody has ever actually seen a flush cause a problem.

Flushing is the best way to change fluid in most any transmission. There is no pressure....all it does is use the transmission's own pump to suck in the new fluid and pump the old fluid out. So it won't rupture seals or anything like that.

I've seen it done on many vehicles that had over 100k and had never been changed before with no problems.

One example that I know I've told here before: When we were about to get our first flush machines, they demo'd them for us on a few cars. Finally, someone asked just how well they cleaned on higher-mileage transmissions. The BG guy asked if we had one that was in for a trans problem, and we did: An high-mileage Aerostar (or maybe a Windstar, it was a minivan) that the tranny was SMOKED. Was already diagnosed and approved for overhaul. So he hooks up the machine to this van, does the flush.

Now remember, this transmission had already failed, and the fluid was stinking-ass black.
The tranny guy that was working on it then pulled it out and disassembled it.....it was unreal. He hardly even had to clean up the parts that weren't getting replaced in the rebuild. It was practically spotless.
My trans guy for my team then told me that the flushes were going to be great for customers, but they were going to cost him a lot of work down the road.

Convinced me.

Moral of the story: If you still think flushing a high-mileage tranny will cause a problem, then don't do it. Simple as that.

But if you are doing the fluid change when you're supposed to, then definitely flush it...it's the best way by a long shot.

 

[sdifox]

Originally posted by: Pacfanweb
The "flushing loosens up grime and causes failures" is pretty much a myth. Every mechanic I know (including myself) has told people that, but nobody has ever actually seen a flush cause a problem.

Flushing is the best way to change fluid in most any transmission. There is no pressure....all it does is use the transmission's own pump to suck in the new fluid and pump the old fluid out. So it won't rupture seals or anything like that.

I've seen it done on many vehicles that had over 100k and had never been changed before with no problems.

One example that I know I've told here before: When we were about to get our first flush machines, they demo'd them for us on a few cars. Finally, someone asked just how well they cleaned on higher-mileage transmissions. The BG guy asked if we had one that was in for a trans problem, and we did: An high-mileage Aerostar (or maybe a Windstar, it was a minivan) that the tranny was SMOKED. Was already diagnosed and approved for overhaul. So he hooks up the machine to this van, does the flush.

Now remember, this transmission had already failed, and the fluid was stinking-ass black.
The tranny guy that was working on it then pulled it out and disassembled it.....it was unreal. He hardly even had to clean up the parts that weren't getting replaced in the rebuild. It was practically spotless.
My trans guy for my team then told me that the flushes were going to be great for customers, but they were going to cost him a lot of work down the road.

Convinced me.

Moral of the story: If you still think flushing a high-mileage tranny will cause a problem, then don't do it. Simple as that.

But if you are doing the fluid change when you're supposed to, then definitely flush it...it's the best way by a long shot.

So is flushing the more expensive one or the cheaper one? I am getting really confused here by terminology my uderstanding is that the cheaper one where they just hook up a machine is called flushing as opposed to ripping the tranny apart.

 

[Pacfanweb]

^yes, you're correct. It's less labor to hook up the machine than it is to drop the pan, clean the old gasket off, change the filter/screen, and reinstall. Plus, the flush is better, because your average trans has 12-14qts of fluid....but you only get about 4 out of the pan; The rest is in the torque converter. Most converters can't be drained. Some can, but not most.

Flushing gets all the old fluid out. Plus, they usually put some cleaner in first and let it run awhile to get all the crud out....not that there is really much crud that builds up in a healthy transmission anyway...tranny fluid has LOTS of detergents in it. If you have a lot of sludgy-type stuff in your transmission, you have a problem.

 

[sdifox]

Originally posted by: Pacfanweb
^yes, you're correct. It's less labor to hook up the machine than it is to drop the pan, clean the old gasket off, change the filter/screen, and reinstall. Plus, the flush is better, because your average trans has 12-14qts of fluid....but you only get about 4 out of the pan; The rest is in the torque converter. Most converters can't be drained. Some can, but not most.

Flushing gets all the old fluid out. Plus, they usually put some cleaner in first and let it run awhile to get all the crud out....not that there is really much crud that builds up in a healthy transmission anyway...tranny fluid has LOTS of detergents in it. If you have a lot of sludgy-type stuff in your transmission, you have a problem.

So, go with the cheaper one, got it.

 

[Elstupido]

Pac, I had the tranny flushed on my 93 Chevy pickup at around 140k. The very next day the tranny started leaking like a sieve. One of two things happened, they either didn't refill it properly, or the flush caused the failure.

I talked to the BG rep, and got nowhere. I also thought of taking them to small claims court ($2500 replacement tranny) but that might have been a tough one. The fluid had been changed per GM service recommendations, every 60k, and had absolutely no problems.

The quick lube places around here now refuse to do a flush on a vehicle with more than 100k, if that tells you anything.

 

[Pacfanweb]

Originally posted by: Elstupido
Pac, I had the tranny flushed on my 93 Chevy pickup at around 140k. The very next day the tranny started leaking like a sieve. One of two things happened, they either didn't refill it properly, or the flush caused the failure.

I talked to the BG rep, and got nowhere. I also thought of taking them to small claims court ($2500 replacement tranny) but that might have been a tough one. The fluid had been changed per GM service recommendations, every 60k, and had absolutely no problems.

The quick lube places around here now refuse to do a flush on a vehicle with more than 100k, if that tells you anything.

I'd love to know how you think that changing all the fluid caused a leak, other than maybe at the cooler line fittings they take loose to flush it. Of the failures that flushing is supposed to cause, leaking isn't one of them. Supposedly, flushing a high-mileage tranny *could* dislodge some mythical sludge inside, and gum something up and cause a failure.
It doesn't cause a leak....unless you/they replaced the fluid with maybe some synthetic...that's generally considered a no-no in a high mileage vehicle.
But I fail to see how flushing, particularly with a BG machine, caused a leak. The machine doesn't have any pressurization.....it uses pressure from the tranny's own pump to move the fluid.

My guess with your local lube shops is, they got tired of people bringing in stuff that already had problems, and then tried to get them to pay for the repairs.

Happens all the time with all kinds of repairs....people simply look harder and notice more after their car has been worked on. Many, many times, I've seen people complain about things that were absolutely impossible for us to have affected, yet they thought that just because we touched it, we caused it.
I can't tell you how many cars I personally worked on that I pulled into the shop, left the door open or the hood up for less than 30 minutes, and the battery was stone dead when I tried to pull it out.
No way in hell I caused it, but most times the dealership would buy the person a new battery anyway, knowing damn well it already was weak before it got there.
I've seen people nit-pick paint work that looked better than the rest of their car's factory paint...they found one almost microscopic piece of trash and griped.....but they didn't look at the car anywhere near that close when it was new.

Again, happens all the time. Sorry you had a problem, but I don't see how it's anything other than a coincidence.

BTW, why did you need the transmission replaced for a leak? If it had a leak that couldn't be fixed, you already had a problem before you took it in.

edt: Oh, and why, if you had the tranny serviced every 60k, did you have it flushed at 140k....only 20k after the last service?

 

[chucky2]

Originally posted by: Elstupido
Pac, I had the tranny flushed on my 93 Chevy pickup at around 140k. The very next day the tranny started leaking like a sieve. One of two things happened, they either didn't refill it properly, or the flush caused the failure.

I talked to the BG rep, and got nowhere. I also thought of taking them to small claims court ($2500 replacement tranny) but that might have been a tough one. The fluid had been changed per GM service recommendations, every 60k, and had absolutely no problems.

The quick lube places around here now refuse to do a flush on a vehicle with more than 100k, if that tells you anything.

This is why 1.) you keep on a flush internval every 30k mi. so varnish/crud doesn't build up in your transmission, and the seals don't start degrading due to trans fluid add pack depletion, and 2.) when you have the flush done every 30k, you make absolutely sure they don't use any cleaners or additives, just the proper fluid - that is all that is needed, nothing else.

Fast acting solvents that are going to be needed to have the quick effect on built up crud/varnish (which will only be there in transmissions that have not had proper fluid changes done on them, meaning the fluid add pack has depleted, meaning the seals are now going to be degraded) during the flush, are not going to be good for those degraded seals, they should be considered to harsh for use. BG sells bottles of flush additive because BG is in the business of making money, and the shops that use them also like to make money. Neither will be able to see into the future when your trans starts dying a premature internal death do to using their products that were never needed in the first place.

1.) Flush every 30-40k mi.
2.) Native correct fluid.
3.) No additives before or after.
4.) Very long trans life.

Chuck