So... total fill for these trans is like what, 14Q? but on the box for the AT Filter Kit from O'Reilly it says service fill 5Q, so basically dropping the pan and changing the filter will refresh about 1/3 of the fluid.

My plan is to take it to the shop with the filter, fluid, and a new Dorman 265-813 trans pan that has a drain plug. Then, I'll periodically (probably every time I change my oil which I do at 5K) do a drain and fill until the fluid looks nice when checked from the trans dipstick.

Is this a good plan? I know I could do an actual flush but I'm hesitant to do that on a transmission with 145K that has not been maintained. The current fluid is nasty and I have some what I think to be torque converter shudder, and the transmission just doesn't feel great in general.

I'm using Valvoline Mercon V fluid if that matters.

Thanks in advance for any advice

Drain the torque converter if you want to drain nearly all of it at once, or find the process posted here for removing the cooler line and using the transmissions pump to pump it all out.

Hang the included gasket up on a wall, and continue to use the reusable one that is already there, and no RTV. The reusable one is coated steel, so you can make sure it is still the reusable one.

Valvoline is not a licensed Mercon V fluid. Notice how it's actually called: "ATF for Mercon V Applications". Personally, I would use Motorcraft, Castrol, or SuperTech. There are certainly others, but I've used all three of those with no issues. Otherwise, your plan is fine.

Would Valvoline Maxlife-D be a better option? I don't think we stock "real" Mercon V in the auto parts store I work at. There's Motorcraft, but it's LV, so that's entirely different, right?

I tried to look up trans fluid on the site, but both it shows are obviously wrong!

Yeah, don't use LV. It's only for 2008 and up cars.

As for Maxlife, I'm not a fan of one-size-fits-all fluids, especially when there are plenty of "proper" fluids available.

You work there and they wouldn't order a case of fluid for you?

Do your search for a vehicle specific fluid, if it doesn't give you Mercon V, add a year or 2, like try 2002. Should be official by then.

Valvoline was "official" at one time. Until I guess they decided not to pay the licensing fee. I used it in the past, but chickened out and went for the "official" Supertech the last time I changed. Cheaper there too.

I could order it but I was hoping to have my tranny fluid changed today.

And I'll use it for now but when I run out of Valvoline Mercon V since I'll be doing frequent drain&fills, I'll order Motorcraft Mercon V.

Worrying about who's paying for licensing and who isn't? Damn, I thought I was on BITOG for a second there!

Haha too true. Though, it does seem Valvoline changed the fluid from full synthetic to a synthetic blend when they no longer had the licensing, all the while keeping the same part number, though the label is slightly different, so that's a bit misleading. Still, it's gotta be better than the 20 year old fluid!

BITOG isn't just a website, it's an addiction.

I'm sure the Valvoline product will be fine, I just prefer to use licensed/approved products.

My only complain with the Valvoline fluid is the smell. It smells like used up trans fluid right out of the bottle. For that reason alone I won't use it. Not when there are so many licensed Mercon V fluids available. Hell, even the house brand at some of the local stores offers a licensed Mercon V.

If a product is licensed to meet a specification, it will serve the intended purpose that the specification applies to. Given this, I am partial myself to using a product that meets or exceeds the Ford Mercon V specification for my car (see signature). However it is wise to use the same fluid consistently in your transmission and not shift brands. The reason for this is that the additives used to meet the specifications are different depending on the manufacturer. Your clutch packs in the transmission are soaked in the same fluid, and when you shift to a different brand, the differing additives can lead to issues with shifting until the new fluid and the clutch material "marry". Given that the fill from empty is around 14 quarts in most model years, so much fluid is available that shifting to a different fluid is not a massive issue. But your clutch material can be affected by fluid choice, and as a result staying with one brand is recommended. This same aspect is true of most fluids used in our cars. But the most critical application where sticking with one brand is in coolants where if the anticorrosion breaks down, the end result is destruction of the heads and the engine in short order.

That place is far to anal for my liking, I quit cold turkey...

As far as always using same brand, again too anal for me... For last thirty plus years, I've used a little bit everything, never a issue(the prev 20 yr I generally stuck with one brand)...

My favorite is using Type F in AOD & AODE... There's a never apart(other than shift kit) Type F dosed Super Coup AOD around here that has something like 85K miles and over 700 drag strip passes... AND that includes a season of nitrous, still works fine... Used F in a slipping AODE from 33K mi to 131K mi, it finally died from a leaking pump to housing gasket...

Go on the ford website and find a distributor for Motorcraft parts. You may have to put in a larger city. Some of them have a no-frills counter in some warehouse district and will give great prices on fluids and parts. You can be sure you are getting the right stuff that way.

If not opt for a licensed Mercon V fluid such as Castrol or Supertech (yes, it is licensed). I don't suggest generic fluids but likely your transmission won't explode. Maxlife ATF is lower viscosity, again it is a BITG thing but many use it with no issue.

Ford is pretty adamant about their warranty- Mercon V or else. I use the Motorcraft product in very high mileage transmissions(for friends and family too) with a 30K OCI and I have no complaints. I pay a bit more than supertech from my distributor.

Changing fluid is a good idea because it removes particle/residue load from the system, even if the fluid runs cool. The electronic solenoids could actually change their conduction patterns if too much metal is floating around. Nothing will happen suddenly but pressures here and they may reduce causing weaker application of gears and more heat. This creates more particle load, etc. No AT will last forever, it is a wear item, but you can maximize its life.