I want to do a transmission flush on my Trailblazer but I'm afraid with really no knowledge of the maintenance history and the fact that I have 145K miles on it, Would doing a flush actually hurt my transmission like cause slippage? The last time I check the trans. fluid was like at an in between color, not bright red but not totally black more like reddish brown. I just thought I'd throw it out there to check with you guys who know way more about our vehicles than I do.
Can I do a Trans. Flush with high miles?
- Thread starter LouisTB
- Start date
Sparky
Member
- Dec 4, 2011
- 12,927
Nah. Just don't do a machine reverse flush as that forces crap off the filter and shoves it backwards into the guts of the trans.
This is how I did mine. Works great to get a total fluid change and near zero risk.
At the color you're seeing it probably has been changed once, or at least partially via pan drop, but it should be done again regardless.
Personally I've always used Valvoline max life Dex/Merc (red jugs) but any decent Dexron VI fluid should be OK.
This is how I did mine. Works great to get a total fluid change and near zero risk.
At the color you're seeing it probably has been changed once, or at least partially via pan drop, but it should be done again regardless.
Personally I've always used Valvoline max life Dex/Merc (red jugs) but any decent Dexron VI fluid should be OK.
Mooseman
Moderator
Mine was brown when I did my own flush (like in the video). That's been like 5 years now, all good.
Flush machines are evil.
Flush machines are evil.
Ahhh okay yea I was just a bit worried cause I don't know anything about transmissions so I just wanted to get a little reassurance that I wouldn't be screwing something up.
Funny thing is the place I work at has one and I was thinking of using it but now I know not to go near that thing hahaha.
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swede
Member
- Jun 22, 2014
- 1,576
I think you have to look at the pan, I know I had to.
I did my own flush on my previous Volvo V70R auto with 110K miles on it, no problem with the tranny after. Flushed with 18 L (4 gallon) Mobile 1 ATF Dexron before I got the color in the last picture. I use a clear hose so I can see when it starts to come air bubbles so I can turn off the engine and not damage the tranny from running dry.
Sounds like I got my next repair after I do my spark plugs. Then probably would be a good
Yea makes sense. I'm glad to know that a transmission flush is a relatively easy thing to do, given that I'm probably gonna be doing it myself. Really need to find some car friends. Would make this job go alot smoother haha
I think the whole high mileage flush warning is a myth. I've flushed some of the nastiest, burntiest, super decrepit trans fluid known to man and haven't had an issue. I wouldn't be surprised if the myth started when someone brought their slipping trans in for a flush (in hopes to fix it) and when the trans flush didn't fix it, it was the flush that made the trans slip. People be crazy like that yo.
You say you got a machine at work, eh? If it's the type that runs off of the trans pump and is tee'd into a cooler line, they do the same thing that our diy version does just in a lot less time and a lot less mess. Those machines won't allow reverse flush.
You say you got a machine at work, eh? If it's the type that runs off of the trans pump and is tee'd into a cooler line, they do the same thing that our diy version does just in a lot less time and a lot less mess. Those machines won't allow reverse flush.
I'm not quite sure if it did or not but our shop has a policy that we can't do transmission flushes if the vehicle is over 120,000 miles. It's a whole liability thing. Thought I should include a picture of the transmission fuild color at its current state. I just went out and did this.
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hockeyman
Member
- Aug 26, 2012
- 726
Here: https://www.gmtransmissionparts.com/4l60e-Filter-Pan-Style-Guide/
Also, for longevity of a/your trans, you should consider a cooler for it.
I was actually thinking about doing that. But I couldn't find a good video on how to install one. And what cooler would you recommend?
I asked the guy at my shop that is basically an encyclopedia of car knowledge and he said it could be bad to flush all the fluid out because it could cause the clutch packs to slip because of the new fluid. He said id be better off just dropping the pan, change the filter, replace the gasket, and clean out the pan. I just really don't want to screw up my transmission and have to by a remanufactured one.
Okay I just want to be absolutely sure. Also sorry if I'm bugging anyone with all my questions. His reasoning was that with a high mileage transmission, all the grit from the clutch packs within the older fluid is what's keeping the transmission shifting like it does now. He said flushing the transmission would take all that grit away and the older clutch packs could not grab as well with new fluid in it. I feel like I'm overthinking it way too much.
Sparky
Member
- Dec 4, 2011
- 12,927
I've heard that explanation. My response to that is if you're relying on grit floating in your fluid for your transmission to work, well, that grit will also tear other stuff up and the trans won't keep working much longer anyway. Also, the filter should be keeping said grit from floating in the fluid in the first place.
My brother's first car had mud for fluid and started slipping horribly. Flushed it with new fluid and it cured it.
My brother's first car had mud for fluid and started slipping horribly. Flushed it with new fluid and it cured it.
Mooseman
Moderator
I think even ChrisFix mentioned that if the trans is relying on the grit in the fluid to work, then it's on its way out anyway.
My current work says the same thing and I think that stems from butt wipes who come in for a flush without saying anything about any problems and then saying that the flush messed up the trans. Every other shop I've worked out did the flush. That's how I know it won't mess up a high mileage vehicle (that does not have a preexisting problem).
I hear you on that, shit aint cheap.
You're not bugging me, I have respect for peeps who want to learn things. I heard that exact same spiel back in 1995 and thousands of flushes later still haven't see it for myself. I'm also still waiting for all of my seals to blow out since I switched to synthetic oil. It's been 160K miles so should be any minute now LOL.
I feel that liking this post wasn't enough, had to quote it and type this just to show how much I approve.
Hahaha I guess you have a point there. Well I guess that settles that, I'll make sure to follow your video to make sure I get it right. Also wanted to thank you for your help.
Also, someone in the thread had recommended putting in a transmission cooler. I was actually thinking of doing that and was wondering if you had ever put one in a Trailblazer and could recommend one you liked? Being from Tampa, it probably wouldn't be a bad investment.
Wanted to thank everyone who replied to my thread. All the suggestions and reassurance really helped a lot in my decision to go forward with the flush. I'm really looking forward to getting to do it.
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hockeyman
Member
- Aug 26, 2012
- 726
Is it super necessary to flare the transmission lines? I remember practicing it in college....was not a fun time.
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jsheahawk
Member
Follow that video if you don't have access to a machine. Great, great video.
The first time I did mine, I bought both and took the wrong one back.
hockeyman
Member
- Aug 26, 2012
- 726
I made my own fuel line once on a carburetor and didn't flare the line when attaching it a hose. Instead, I put a thin coating of grey silicone on the line, then attached the hose with a clamp. Didn't had an issue for the following years that I owned it.
I can't see the trans line being under any type of high pressure, so you can probably get away with just a clamp. Although, I have a flaring tool, so I'd use it just for self-assurance.
I can't see the trans line being under any type of high pressure, so you can probably get away with just a clamp. Although, I have a flaring tool, so I'd use it just for self-assurance.
Yea I just wouldn't want to get to that part, flare the ends and end up now having a screwed up flare that would restrict flow or possibly screw up the entire line especially the line that you have to flare on the vehicle.
Mooseman
Moderator
Not necessary to flare. To be safe, just double clamp the hoses to the lines. It's also not super necessary to remove the bumper cover neither. Use a fender cover/protector to protect it.
Here's a chart showing transmission longevity vs. temperature. The cooler the better.
Here's a chart showing transmission longevity vs. temperature. The cooler the better.
AzTruckGuy
Member
So my TB has 96k miles on it, and this was next on my list to do. Going to change out the filter and do the fluid change this way
I am also going to change the radiator fluid, so if you guys are saying that a flush is a waste for the tranny, what about the radiator?
I am also going to change the radiator fluid, so if you guys are saying that a flush is a waste for the tranny, what about the radiator?
Mooseman
Moderator
Okay that will make my life a lot easier knowing I dont need to flare it.Not necessary to flare. To be safe, just double clamp the hoses to the lines. It's also not super necessary to remove the bumper cover neither. Use a fender cover/protector to protect it.
Here's a chart showing transmission longevity vs. temperature. The cooler the better.
eutechnyx
Member
- Mar 31, 2012
- 375
I did a pan drop and filter change on my truck a couple years ago. My dipstick tube was rusting out which is the reason i changed mine. replaced the dipstick tube/dipstick and dropped the pan and filter and installed the pan with the drain plug for future changes.
Just bought my truck second hand and it just hit 200k. My father-in-law told me he did not do a flush because the transmission fluid was too old and was afraid it would slip. It was doing fine but was running hot (230's) and was not pulling that hard. I changed the filter and flushed it with Dex IV and it was slipping a little (more like shudders). I drained out two quarts of fluid and dumped in two bottles of Lucas Transmission Fix and it pulls hard now and the temp is down to 210.
I think it could be cooler but I have cooling problems with the engine right now and there is still a little slip, but I figured running it with new fluid another 30k or so while save $$ and find a reliable mechanic to replace the clutch packs is better than leaving the black water in and pay for an entire trans later.
I think it could be cooler but I have cooling problems with the engine right now and there is still a little slip, but I figured running it with new fluid another 30k or so while save $$ and find a reliable mechanic to replace the clutch packs is better than leaving the black water in and pay for an entire trans later.