Trans Flush

[Wooluf1952]

This is from the 2012 July/August Truck Trend Magazine about a TB SS, but I believe it's relevant to all:

Question: I have a 2008 Chevy TrailBlazer SS RWD with the 6.0-liter V-8 and 4L70E automatic, with 42,200 miles. The owner's manual says the transmission fluid and filter need to be replaced at 50,000 miles. Someone told me that, if I go somewhere like Firestone so they can perform a trans flush, they don't replace the filter, saying the flush has chemicals to clean it out. If I ask for the filter to be replaced, they say it will be an additional charge, as they have to remove the transmission pan. If I'm getting the fluid flushed, does the filter also need to be replaced? Would a dealership perform both fluid flush and filter change for one price? On a side note, when should I change the rear diff fluid? The owner's manual doesn't specify.

Answer: General Motors, and every other manufacturer I can think of, does not recommend the flushing of the engine or transmission, even though some dealership service departments sell it anyway. (Hard to believe, I know.) At 50,000 miles, the designated service is to drop the transmission pan, replace the filter, reassemble, and fill it up with new fluid. In your case, the "drain and fill" will replace about 5 quarts, and DEXRON-VI is the one and only automatic transmission fluid to be used, according to GM.

The presumed advantage to flushing is it replaces all the fluid in the transmission. The drain and fill on your TrailBlazer replaces about 5 out of 11 quarts. But in my opinion, the risks of flushing outweigh the benefits due to the possibility of contamination caused by the flushing equipment and/or use of improper fluid. Do the manufacturer's recommended service with DEXRON-VI and a new filter, and you'll be fine.



Read more: 2008 Chevy TrailBlazer SS RWD Transmission Flush - Truck Trend Garage​

 

[Scott750]

That's my question to Truck Trend! Took them months to respond. I hit 50k miles when they did. I ended up just doing a pan drop and filter change like they recommend. The flushing of the Trans was general advice from my s10 days and the local shops always pushing the service on me. It made sense to replace all of the fluid than part of it. But they never changed the filter and would charge me almost double the service price which never sat easy with me.

 

[northcreek]

IMHO You flush your transmission for the same reasons that you flush your toilet...gets rid of all the crap...just sayin',Mike.

 

[Sparky]

I prefer to pump out all the old fluid (or pretty darn close to all of it), drop the pan, put a new filter on, then refill. 164k miles on the Trailblazer, 168k-ish miles on the trans in the Camaro, both going strong. I guess I'm doing something right

 

[Wooluf1952]

I look at it the same as wasting money on 3K mile oil changes: If it helps you sleep at night and you have the money, go for it.

 

[northcreek]

I look at it the same as wasting money on 3K mile oil changes: If it helps you sleep at night and you have the money, go for it.

That's a great point,I've always been anal about auto transmission service,flushing,filters,oil temp gauges and the like and for all of this I have had as many transmission problems as the next guy...so yeah...if it makes you feel good...do it but,it doesn't guarantee you anything...Mike.

 

[NewfieEnvoy]

I spoke to my local garage and their advice was the only reason to flush an auto trans was because of some issue you are trying to resolve, most likely fluid contamination. They would attempt a full flush and test the results before a major service or rebuild. Other than that, for general maintenance, your just asking for trouble. They said drop the pan, change the filter, and top up.

 

[Cable810]

Answer: General Motors, and every other manufacturer I can think of, does not recommend the flushing of the engine or transmission, even though some dealership service departments sell it anyway.

I went to the dealership regarding some questions I had and they suggested a Engine Flush to get rid of the crap thats probally built up.

 

[Sparky]

I went to the dealership regarding some questions I had and they suggested a Engine Flush to get rid of the crap thats probally built up.

The only build up should be typical wear stuff collected in the filter.

 

[Pittdawg]

The only build up should be typical wear stuff collected in the filter.

I had the stealership flush, replace the fluid and change the filter a few months back, right around 60k. I must say the tranny appears to shift a bit smoother now.

 

[xj2202009]

at 50k you could get away with filter and pan drop specially if you don't tow. Wipe the dipstick in a white napkin and check the integrity of the, should leave a red stain and should not smell like burnt oil. The filter needs to be changed or do nothing at all. I just completely flushed mine at 100k even though there was alot of slug at the bottom of the pan, the worse stuff was glue to the actual inlet of the filter.

 

[gmcman]

I just don't understand why you would replace 4 out of 12 quarts of tranny fluid? I know what the shops say, but who's vehicle is it? How much is 8 more quarts?

14 total to flush just to be safe and piece of mind.

Purchase a Hayden 397 fitting, not sure if the SS has the same port but if not, pull the passenger line, attach a hose, and pump it out. With the fitting you can tap the drivers side and flush the cooler.

I did mine not too long ago and it was a snap. I believe if I had a bucket of 14 quarts of new fluid I could have sucked in the new and collected the old at the same time and shut it down when the new fluid ran out, may try that next time.

Here's a thread I did and considering the color of the fluid, no way would I have left 3/4 of that in the trans.

Trans fluid change

 

[Wooluf1952]

I can understand a complete flush if the fluid is really dirty and/or smells burnt. But, then the filter should also be changed.

 

[fadyasha]

I wouldn't take any risks with my Tranny or Engine. I drop the pan, change the filter and top her up again

 

[WarGawd]

I believe if I had a bucket of 14 quarts of new fluid I could have sucked in the new and collected the old at the same time and shut it down when the new fluid ran out, may try that next time.

Here's a thread I did...
Trans fluid change

I kinda had the same idea, but I thought May03LT had a good point in your other thread about using more fluid that way. (I also have some doubt that there is any "suction pressure" on that side, if the return line is just draining back into the pan somewhere, but I'm not sure of that part)

And as I posted in the other thread, a possible option to the Hayden 397 for the same price for those who haven't bought one yet may be Life Automotive Products - Smart Blend Synthetics, Trans Flush, ATF Products

 

[gmcman]

I kinda had the same idea, but I thought May03LT had a good point in your other thread about using more fluid that way. (I also have some doubt that there is any "suction pressure" on that side, if the return line is just draining back into the pan somewhere, but I'm not sure of that part)

I agree, you are likely correct...not worth trying if we're not sure.

What I did was pump it out, add 1 gallon through the dipstick tube, pump it out, add 1 gallon, pump it out, then top off.

 

[marinegrunt]

I have always completely flushed all of my vehicle's transmissions every 50k and I have never had any transmission issues except for one vehicle I purchased with high miles. From the looks of the fluid I could tell it had never been changed. I flushed it and still got another 100k out of it before it had problems. From what I've heard, the reason the myth of flushes causing transmission failure is out there is because most people don't do regular maintenance on their transmission. They end up doing the flush once they notice the transmission slipping, jerking, etc. At this point it's too late. Six months later their transmission is toast, which it would've failed anyways, so they lay the blame on the flush.

Over time, the protective additives in transmission fluid starts to break down even at the normal operating temperature of 200 degrees. When towing, the operating temperature rises which means the transmission fluid breaks down even faster. If you tow often it's recommended you change your fluid sooner than 50k.

The number one reason for transmission failure is due to overheating. Stacked aftermarket transmission coolers are an good way to prevent overheating. Stacked coolers allow transmission fluid to bypass the cooler if the temperature drops too low. I've installed aftermarket coolers on all of my vehicles I tow with and have never had transmission problems with those vehicles.

Just dropping the pan and filter only replaces 4 to 5 quarts of fluid leaving the other 60% or so still in the torque converter. This other 60% of fluid could possibly be contaminated. It's guaranteed that the chemical properties are broken down and not 100% effective. Mix this with the new 4 to 5 quarts of fliud and the change didn't do much except for the new filter.

It's my opinion, to flush all the transmission fluid as regular maintenance is the way to go to prevent transmission failure, but to each his own. As the say though, "the proof lies in the pudding" so I will continue doing flushes. I feel that is what has kept my vehicles from having any transmission issues.

 

[gmcman]

It's my opinion to flush all the transmission fluid as regular maintenance but to each his own. As the say though, "the proof lies in the pudding" so I will continue doing flushes. I feel that is what has kept my vehicles from having any transmission issues.

I completely agree.

Something else I have recently encountered and I posted this also....I had slipping or a flare at the 2-3 shift at about 160K. I drive mine sometimes in a spirited fashion but not terribly hard and tow on occasions. I have flushed my fluid at roughly 30-45K intervals and never had a problem.

When I added the vette servo at 173K which granted adds pressure to the clutches, I also changed the seperator plate which IMO, made all the difference. These plates wear out, plain and simple...all of them do. I had a check ball pushed through one of the holes and the rest were not too far behind.

My slipping wasn't from all from clutch wear, it was mainly from lack of pressure and when the plate wears, fluid finds it's way in places it shouldn't affecting the shift and most importantly, the life of the trans. Now it's safe to assume that at 173K miles the clutches have worn, but had I changed the plate and the two accumulator pistons at maybe 90-100K, vette servo install....then I would have alot of life left in my trans at my current mileage. I expect the trans to last much longer now than originally expected after I did all this, it now acts like a new trans so time will tell.

In stock trim, we have nice, plush, soft-shifting transmissions and will wear quicker than one that's shifts are a little quicker and firmer...that's the trade-off.

The job is slightly messy but the reward is ten-fold. I would highly recommend to install a new seperator plate, maybe even the upgraded Sonnax accumulator pistons, and the vette servo at about the 90-100K mark. Actually replacing just the vette servo at any point is a step formard IMO.

Do this and I cannot imagine any negative effects, only a greater time between a rebuild.

Back to the topic at hand, A complete fluid change is better than a pan drop only. We have doomed transmissions in our stock form and failure rate is high under 200K for the 4L60E the way it's setup in our platforms. All tranny's are doomed, just ours is sooner than most.

 

[Sparky]

I'm aiming for over 200k out of mine and I have 164k already. At around 120k I did install the sonnax accumulators, transgo hardened separator plate, vette servo, etc so I'm good there

 

[Pittdawg]

I have noticed recently it takes quite a bit more effort to shift from park to reverse when parked on an incline. Is this anything I should be concerned about?

 

[Wooluf1952]

I have noticed recently it takes quite a bit more effort to shift from park to reverse when parked on an incline. Is this anything I should be concerned about?

That happens to all vehicles. The steeper the hill the harder it is to move the shifter out of Park. It's called torque lock. It's from the pressure on the Parking Pawl in the trans. The only way to avoid it is to set the parking brake before putting it in Park.