Transmission fluid change....Remove pan or not?

I'm getting ready to change the auto tranny fluid in my 99 XJ, it's nearing 90k miles. The fluid on the dipstick is relatively clean and does not smell burnt, but I just bought a camper, getting ready for some towing, and want to make sure the fluid is fresh. A few months ago I change the TC fluid and it was very clean so apparently the previous owner took good care of it.

But the dilemma is, should I remove the pan, clean it and the magnet, and replace the filter/screen? I just did it to my '00 Caravan with 140k miles and it was scary how dirty the pan and filter was, so it makes me feel like I should do it to the XJ too. Am I just being paranoid?

Also any opinions on the best quality fluid brand would be great.

Leica99XJ said:

I'm getting ready to change the auto tranny fluid in my 99 XJ, it's nearing 90k miles. The fluid on the dipstick is relatively clean and does not smell burnt, but I just bought a camper, getting ready for some towing, and want to make sure the fluid is fresh. A few months ago I change the TC fluid and it was very clean so apparently the previous owner took good care of it.

But the dilemma is, should I remove the pan, clean it and the magnet, and replace the filter/screen? I just did it to my '00 Caravan with 140k miles and it was scary how dirty the pan and filter was, so it makes me feel like I should do it to the XJ too. Am I just being paranoid?

Also any opinions on the best quality fluid brand would be great.

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If you haven't inspected the filter, magnet, and sump yet; do so. Or at least clean them out (the pan will usually wipe clean with a bit of brake cleaner. Blow the filter clean with some brake cleaner as well. The magnet can be wiped clean with paper towels to get the metal "fuzz" off.)

You're not being paranoid - it's a good idea to check and make sure. Once you know things have been cleaned out, you're probably good if you check and clean things every other change or so.

Brand of fluid? I typically use Valvoline, since it's what's readily available and a good choice. Castrol or Chevron are also on that list.

I remove the pan every other fluid swap. It's a PITA to do it every time.

Ok, I'll go ahead and remove the pan....Any tricks to it?

Do I need a gasket or or RTV?

I prefer to use a gasket on "maintenance access" parts like this (and axle covers,) because I find it easier to clean off than RTV. You should be able to pick up a gasket without too much trouble at the local.

The biggest trick is that once you have all of the screws out (M6-1.0x15m/m, if you need to replace any...) is that the pan still won't come all the way out. You'll have some clearance to move it, and what is keeping the pan in place is the O-ring joint in the dipstick tube. Wiggle and turn the pan until the dipstick tube comes apart, it's going to take a minute.

Clean the O-ring end of the tube (the part still attached to the vehicle) and replace the O-ring if necessary. Clean the mating bit with a bottle brush or a gun barrel brush (I think either a 16ga or a 20ga shotgun brush will serve here - I don't recall. I like the bronze brushes for this sort of thing.) Lubricate the male end (with the O-ring) using grease or never-seez before reassembly, as that will make it easier to remove next time (repeat the clean and lube each time you take the pan down.)

I find it easier on my sanity to install three or four studs (M6-1.0x25m/m) spaced around the sump perimeter. The holes in the gasket are usually a bit undersize, so you can push the gasket onto them. Place the pan over the studs, then just hold it in one place while you get nuts started on the studs. Start all of the screws by hand, then tighten them to spec once you have them all started (spec is on my site in the Tech Archives.)

The cork gaskets will usually strip right off with a razor blade, you may need a "brass toothbrush" around where you put the studs if you do that.

Thanks for the tips, and hey I just realised when I looked at your site that I ordered the battery cables from you awhile back, great product! Unfortunately though, after installing the cables I have realised that my starting hesitation is due to a bad pressure regulator, I had my fingers crossed that the cables might have cured the problem, a long shot I know haha.

I guess my next project will be dropping the tank and tank skid plate to fix that issue, good times!

If you plan on doing a lot of towing, you might consider one of the universal synthetic trans fluid, they stand up to higher temps better.

Really? From all the searching I've done the consensus seems to be to stay away from synthetics when it comes to the automatic trans. I know autos are very finicky when it comes to fluids, my Crown Vic and Caravan being two of them which require specific fluids. Not sure I want to risk it.

I have the towing package (tranny cooler) and my camper weighs less than 2000 lbs. so I think I'll be alright as long as I change the fluid on a regular basis.

Leica99XJ said:

Really? From all the searching I've done the consensus seems to be to stay away from synthetics when it comes to the automatic trans. I know autos are very finicky when it comes to fluids, my Crown Vic and Caravan being two of them which require specific fluids. Not sure I want to risk it.

I have the towing package (tranny cooler) and my camper weighs less than 2000 lbs. so I think I'll be alright as long as I change the fluid on a regular basis.

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Sounds like you got it handled, and that is a pretty light trailer.

I have always used synthetic fluids, mostly B&M, in all vehicles I used for heavy towing, never any problems.