Dexron 6 and Dexron 3 mixing

[Alex]

I plan to change the trans fluid in my 2003 chevy impala with a 3.4l v6 and a 4t65e per instruction by the user manual. The fluid right now looks fantastic and is bright red. I am going to be using Dexron 6 as the replacement fluid. Since not all of the original dexron 3 is going to come out is it bad for the two to mix together, if so should I just take my car to a dealer to have flushed with a filter change?
Thanks!

Topic

[college man]

You could do 2-3 drain and refills. I’m not a fan of flushes.

[Mike]

A filter change and replacing the fluid that drains is all that’s typically needed.
Dexron VI is backwards compatible.
http://www.acdelco.com/auto-parts/vehicle-maintenance/lubricants/transmission-fluid-dexron-vi.html

Here are Eric’s thoughts on auto transmission service
I[b] don’t believe a ‘flush’ is necessary. Often all that’s required is a drain and refill, a filter if it’s replaceable, especially if you don’t have any shifting issues at this time. There seems to be an obsession with transmission ‘flushing’ as if it’s the cure all. If there’s a problem, sure give it a try, otherwise just the recommended service as directed by the manufacturer should be fine. I have yet to see a factory manual where it says ‘flushing’ is required at a certain interval.
[/b]taken from https://www.ericthecarguy.com/kunena/8-Service-and-Repair-Questions-Answered-Here/50817-f-150-100k-auto-transmission-flush

[James]

agree with Bonnieman. Dex 6 is fine to mix with Dex 3. Just do filter and replaced drained fluid. Dont forget to clean off magnet and put back.

[Alex]

Sorry about late response, been busy with school and work. Thanks for the replies! I’ll do the change with dex 6 and then change it again 30000 miles after with dex 6 then the 3 should be out of there for the most part.

[Author]

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