Auto trans & diff. fluid change, have some ?'s

[risket]

The vehicle in question is a 2000 Jeep Wrangler Sport w/ 4.0L, 79,000 miles. I want to do a filter/fluid change on the transmission, but I have a few questions:

1. The factory service manual says to use ATF+3, but evidently there is a new fluid, ATF+4, which is supposed to be compatible. However, I suspect the fluid has never been changed, so it's probably conventional ATF+3. Are there any dangers with combining ATF+3 dino with ATF+4 synthetic? I won't be pulling the torque converter or the valve body so there will still be some of the old stuff inside.

2. The service manual states that I should use 80W-90 in the differentials for standard use, and synthetic 75W-140 for towing. Are there any advantages to using 75W-140 over 80W-90? I won't be towing anything, and the hardest use it will see is light trail driving and maybe some rock crawling in the future. The auto parts store stocks valvoline synthetic in both weights, should I even consider using AMSOIL or Red Line?

Thanks for the help!

 

[Tempest]

Quote:

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should I even consider using AMSOIL or Red Line?

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Yes.

I would do a cooler line drop type flush with new fluid on your trans to get as much of the old fluid out as you can. Along with the pan drop/filter change of course.

I use Amsoil in my Libery and am happy with the performance. Redline is also top of the line.

 

[ConfederateTyrant]

No harm in mixing ATF+3 and ATF+4 when you do a pan drop/filter replacement. After doing the pan drop, drive for 15,000 miles, then do another pan drop/filter replacement and a cooler line flush with a full synthetic ATF. Amsoil ATF, Redline C+ ATF, and Mobil 1 ATF are good choices and should hold up well enough for you to never need to flush again, as long as you perform a pan drop/filter replacement at reasonable intervals (20,000-30,000 miles).

As for differential fluid, go with 75w-90 since you won't be towing. If you want a touch more protection, see about Amsoil Severe Gear 75w-110, which won't be as fuel inefficient as 75w-140, for when you do rock crawling. Redline 75w-90 would be a great choice as well if you stay with 75w-90. Go with whichever is more available and meets your needs.

 

[pp_rp]

I've had better luck with Royal Purple Max-Gear !!

 

[unDummy]

Regardless of gear oil weight chosen, I would definitely use a synthetic. Driving style, mods, location, and goals would help determine the weight needed.

For the transmission, stick with the ATF+4. Its priced well, performs well, mixes with your old ATF perfectly, and is available in a dozen or so brands already.

Install a drainplug for that ATF pan. A partial drain/refill on an 80k tranny is less then what is needed. 3-4 drains with 10 minutes of driving in between, or a complete flush is required.

 

[meep]

Good suggestions.

The ATF+4 is good stuff... we had a minivan which we did occasional heavy towing with. No AT cooler, but I did have an inline temp gauge for the AT. +4 held up very well and with casual maintenance never gave us any trouble. Do a couple of changes and get the old +3 out of there. It's done.

For the 'ends I'd normally suggest any good 80-90 syn, but rock crawling can wreak havoc with shock loads (free spinning wheel immediately stop as it lands on solid ground. Even harder if it's a stick. If you're serious about this, I'd go with a 140. The amsoil x-110, tho I've never used, sounds like am ideal compromise.

 

[Pablo]

I recommend Amsoil ATF, but if you want to go with ATF+4, that's fine for shorter intervals.

I do however highly recommend Amsoil 75W-110 gear oil.