So you tend to lose overdrive gears first with rfe's, it is likely the clutch packs or valve body accumulator pistons. Two must video watches are here below links, and you need a
synthetic rfe filter upgrade with a metal thread, no more plastic. First things first, yes you will need 8 quarts of redline C+, it is pure rfe honey and will likely solve this. Now, you should drop the pan as well, so good time to find a synthetic filter from thread above and order it, knock the paint off it, purchase a rfe metal thread upgrade, and a sump filter I highly suggest mopar oem for this, and i don't recommend oem for hardly anything, but spark plugs and sump filters yes, do not use oem spin on filter, use the option from the thread above, and now all you need is transmission gasket maker.
Dime to donuts this gets you right, but to get longer use from your rfe have a plan soon to update valve body like the ones below, they have plate upgrades or gasket, if you are going to tune up pressure, you will want a plate, not cheap but will protect that rfe better. The cheaper route is a gasket shift kit w/o tuning psi. This is not a full flush, do not worry about that one bit, like I said if you plan to do this first and a larger fix later your fluid will be like new between the two procedures. You can get a new pan with bolt, this makes changing easier, but costs more every time you swap fluid and it will take more. The good thing about the rfe you can pump fluid right out of the dip stick and do some quick flushes and keep fluid fresh. 4 quarts out and 4 quarts in on any day you are bored.
Hemi395 found these and as far as I'm concerned they are the rfe bible.
Valve Body upgrades.
Rfe weaknesses.
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