Transmission Fluid Change?

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Hoos95

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I’m coming up on 350,000 miles and was curious about changing the transmission fluid, since it seems pretty difficult to get to and “not supposed to be changed,” but assuming it should be done.

Also, I am experiencing some transmissions issues:

1) shudder when accelerating uphill or around 40-55mph - similar feeling as if you’re driving over those painted lines before toll booths or driving on those warning divots on the shoulder of highways.

- possible this can be fixed with new plugs (SP546) and new coils: replacing them this weekend. I will update this if the plugs/coils fix.

2) slipping/creaking sound occasionally when accelerating.

Also, if I were to change the transmission fluid, filter, etc. I’d prefer to do it myself since I’m a DIYer, but couldn’t find any good detailed instructions or pictures on how to do it and how many quarts would be needed.

Thanks in advance for the help!
 
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Vancouver Bob

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99WhiteC5Coupe

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I’m coming up on 350,000 miles and was curious about changing the transmission fluid, since it seems pretty difficult to get to and “not supposed to be changed,” but assuming it should be done.

Also, I am experiencing some transmissions issues:

1) shudder when accelerating uphill or around 40-55mph - similar feeling as if you’re driving over those painted lines before toll booths or driving on those warning divots on the shoulder of highways.

- possible this can be fixed with new plugs (SP546) and new coils: replacing them this weekend. I will update this if the plugs/coils fix.

2) slipping/creaking sound occasionally when accelerating.

Also, if I were to change the transmission fluid, filter, etc. I’d prefer to do it myself since I’m a DIYer, but couldn’t find any good detailed instructions or pictures on how to do it and how many quarts would be needed.

Thanks in advance for the help!


How did you determine that the transmission fluid is, “not supposed to be changed”?
 

Black

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350,000 miles you are rolling the dice either way. I’d be inclined to just leave it with that mileage.
I am presuming you are putting money aside for a rebuild/replacement?
 

MuddySpokes

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While not having direct knowledge with this tranny . . .

I had read several comments that trannies have a high probability of failing shortly after a high mileage lube change. Going theory is that the fresh lube cleans a lot of the built-up stuff which in turn clogs the filter. Recommendation to avoid this is to at least change the filter shortly after the lube change, but do not remember whether 'shortly' is something like 500 miles, or 5,000, miles, or . . .
 
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Hoos95

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I think the best right now is to not mess with the transmission oil, and if it fails it fails.

But are there any other recommendations to fix the 2 issues I’m having?
 

mjp2

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While not having direct knowledge with this tranny . . .

I had read several comments that trannies have a high probability of failing shortly after a high mileage lube change. Going theory is that the fresh lube cleans a lot of the built-up stuff which in turn clogs the filter. Recommendation to avoid this is to at least change the filter shortly after the lube change, but do not remember whether 'shortly' is something like 500 miles, or 5,000, miles, or . . .
That applies to the fluid flush that a dealer would do. They push fluid through the system which could dislodge something and gum up the works.

A simple pan drop, screen replacement, and refill shouldn't have any ill effects. It won't replace all the fluid in the system but at least a decent percentage of what gets mixed in will be fresh and not broken down.
 

Black

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That applies to the fluid flush that a dealer would do. They push fluid through the system which could dislodge something and gum up the works.

A simple pan drop, screen replacement, and refill shouldn't have any ill effects. It won't replace all the fluid in the system but at least a decent percentage of what gets mixed in will be fresh and not broken down.

Under lower mileage circumstances this is generally the case.
But at 350k I would not want to introduce any new sorts of detergents into the system at all.
 

1955moose

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If you don't know the history of the transmission as far as services, your gambling. Especially with the rumble strip effect that is so common on 6r75/80 tranny's. I'm with the others, your well beyond that vehicles life span, consider moving on to another vehicle. It's not an old Victorian house that goes up in value.

Sent from my N9131 using Tapatalk
 

TobyU

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Most all these comments are spot on and as mentioned....not an exact science with high mile original fluid.

The flush machines are most dangerous in this situation and I stay away form them on everything.
You won't have a converter plug drain on a newer one so you will only get half or so out from a pan drop which might be a good thing.
Often when new more slippery (fiction modified) fluid in introduced with no thickening and grit to keep the clutches together, they start slipping. This is why thes old car dealer trick was to put sawdust in a slipping trans. Friction and cohesion.
I don't think the issue is as much clogging the filter. I have had clogged filters and the clutches and trans didn't slip It held 1st or 2nd too long and didn't want to shift unless tou let off and then sometimes not...it would surge up and down before shifting
Changed filter and never a slip problem later and raced that car up and down the roads a lot.

I would do a pan drop and filter change and then do it again in 6 month to a year or 6000-10K miles.

You could pump old out if really dark by popping off line at radiator and pouring fresh in as it pumps out until it gets clear and then change pan and filter.

You could just buy the tube of Dr, Fixit Instant shudder fix and add it.
You are getting converter shudder from old fluid.

I would change it and if it fails...get a used one from junk yard and swap it out.
 

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