How many miles before a tranny flush?

[Stick in Mud]

Hey guys,

I went to get my oil changed the other day for my 2007 Pontiac Grand Prix with 69,000 miles...fella says the tranny fluid is super dark and in need of a change. I don't trust fellas at these places--he also wanted $40 to change a burnt out headlight--but I also don't want to do any damage to the car.

Is this about the right time for a filter and flush? The car has had nothing but normal usage...I'm a complete non-expert when it comes to cars, is there any way I can check this myself to see if it does in fact need a change?

Carmike

[Bigbuck08]

Yes that is the right time for a service. I have a 05 Impala with the 3800 engine and I had mine done at 80K and it was pretty bad, just have them change the filter and fluid DON'T let them Power flush it, The GM Tranny are known for shifting problems after a power flush. I had many people tell me not to power flush and did it anyway and my Impala started shifting hard from first gear into second a few days later! it's never been the same since. I would have the Trans serviced every 50 or 60K but that's just my suggestion. If you stay on top of the fluid changes that car will last forever. I sold my mom a Grand am GT with 80K on it. I told her make sure you keep up on the fluid changes she did and that car is still on the road today runs great! she has 310K with the original motor and trans.

[MuleShack]

Hey guys,

...fella says the tranny fluid is super dark and in need of a change. I don't trust fellas at these places--

I took my truck in to a place to have the tranny fluid flushed and they told me my oil was dark so it probably needed to be changed. I said Funny I just put 3 1/2 gallons of fresh oil in there with a filter about two weeks ago...

[Jeremy airjer W]

Check your owners manual. All the suggested services are in it!

GM recommends new fluid and filter every 60k on all there later model vehicles.

[Stick in Mud]

Owner's manual? Cars have owner's manuals?!?

[Eric Wettschreck]

is there any way I can check this myself to see if it does in fact need a change?

A real quick thing you can do is pull the dipstick. Take a peek and a sniff of the fluid on the stick. It should be reddish/pink and not dark or black. If it smells "Burnt" you have a problem.

Otherwise, 60k miles you should change filter and fluid. I would not recommend a flush.

Heck, come on down to the frozen desert of SW MN, I'll show ya how it's changed. Then we can hit the ice.

[Scott K]

You have ice?

[fishkins]

One thing I can tell you without doubt,,,oil changes are a lot cheaper

than transmission rebuilds. What's that penny/pound thing???

[Eric Wettschreck]

You have ice?

Not a lot, but yup.

[Lip_Ripper Guy]

Just had my F150 flushed at 47k. It's like a new truck.

[corncob]

A private transmission shop (that was repairing my transmission) told me that people are pretty good about changing engine oil,but, forget that transmissions need regular servicing too......The man said that if people got regular transmission fluid changes and full serviving he would be out of buisness....Anything time transmission fluid is dark or smells burnt its time for servicing....Service your transmission about every 20k and avoid repair costs.

[Jeremy airjer W]

20k under "regular" conditions seems a bit excessive but certainly can't hurt.

[fishing tech]

I agree with airjer, If you are towing a lot maybe 20k I do my own and do it at 25k because that is all I do with it is tow. Of coarse it takes me 5-6 years to get to that point. None towing I would go 40-50k. The fluid are so good nowadays you should be fine.

[1968]

Flush is an improper term for most ATF machines. They are usually a passive exchange powered only by the pressure in the trans cooler lines with the engine running. I've "flushed" hundreds without incident. If new fluid ruins your trans, it was likely on the way out. Or the guy doing it sent it out low/high.

If it's really that bad a flush and a filter could be in order. Dropping the pan gets 40-50% of the fluid at best.

Staying up on flushes can reduce the need for filter changes. Most debris is very small and held in suspension by the fluid, passing right thru the filter. If this normal debris is removed on a regular basis, the filter may last the life of the car.

[JOHNBIGDOG]

on a side note, if you have a ford torqueshift, you have to/should replace the external filter at every service. (every 30k)

Ford cvt drain and fill only and replace the High pressure filter every 30K

(these are two I know for certain off the top of my head)

BUT if you read your owners maintenance schedule you would know this.

[Jeremy airjer W]

New subarus are drain and fill only as we'll.

[Stick in Mud]

Ok, so just to check in: I've been told by some people who I've asked in person that I should NOT flush it and should just change the fluid and filter. Apparently, this car (a 2007 Pontiac Grand Prix) might shift hard after a flush but not if I just change the fluid and filter.

Others say a flush is in order.

What's a fella to do?!?

[MuleShack]

It just seems like you are diluting the new fluid by only changing the fluid in the pan. Then the old stuff comes and mixes with it. In my truck there is supposedly more fluid in the lines than in the pan so I would only be changing out 45% of it.

Flushing it the natural way by letting the car pump it out after changing the fluid in the pan and filter seems like the best way.

[Macgyver55]

It just seems like you are diluting the new fluid by only changing the fluid in the pan. Then the old stuff comes and mixes with it. In my truck there is supposedly more fluid in the lines than in the pan so I would only be changing out 45% of it.

Flushing it the natural way by letting the car pump it out after changing the fluid in the pan and filter seems like the best way.

It may be is the "best way" overall but is it the most practical, or necessary?

Maybe on a neglected vehicle, but probably not on a regularly serviced transmission. Its not really all that different than changing the oil on your vehicles engine when you stop to think about it. Many, if not most vehicles have some sort of oil cooler, or remote oil filter that has hoses, coolers and filter bases that hold a fair amount of oil even after draining the system. Not to mention oil that is held in hydraulic lifters, push rods (when present) oil journals in the crankshaft, oil pump and various other passages in the block. I'd guess possibly up to 25 percent or more in some cases. Granted, it is a lesser percentage of the total amount compared to a transmission but still there nonetheless. Does anyone ever run their engine and pour in oil until it is clean? Nobody I know!

Transmissions are somewhat different in that, outside contaminants like fuel, intake air, combustion gasses and condensation are not constantly introduced into them. They are more of a closed system where the only contamination in them is from the normal operation of the internal parts. The inside of a regularly serviced transmission is amazingly clean.

Its when left unserviced that the fluid can breakdown, lose its effectiveness and begin to cause accelerated wear.

If you dont maintain your transmission on a regular interval, flushing it while running is probably a better option for you. If you do it on a regular schedule it is not necessary in most cases. We had many GM vehicles where I worked on regular intervals that had from 200 to 250,000 miles on original transmissions that were in severe duty conditions their entire service life with fluid that often looked perfect. The ones that did fail were usually catastrophic failures (broken hard parts) not related to fluid failure.

[Scott K]

If the fluid is dark, or smells bad, flush and filter. On some models, the torque converter, cooler, and lines can hold more then the pan holds. So just dropping the filter and pan, wont be doing much good.

If the fluid looks ok, and doesnt smell bad, then a pan and filter change is good enough.

If you flush it, just pull of a line, dump it into a bucket, and refull through the filler tube, until the fluid going into the bucket is clean. Dont use a power flush machine!