Best shift quality ATF?

[JT1]

Hello fellow petroleum product junkies, I am on a quest to find the ATF which will produce the smoothest shifts from my 1991 caprice's 4L60 transmission.

At the moment the trans is 45k mi into a rebuild and seems to be shifting fine outside of the 1st into 2nd clunk. Strangely enough this 1-2 clunk or jerk goes away if the gear selector is placed into D rather than OD?

The transmission fluid is clean and dark red but I am uncertain of if it has been changed since the rebuild.

I have considered the following:
Maxlife Dex/Merc
ST Dex VI
ST Dex/Merc
Mobil 1
Valvoline Dex VI
ST Mercon V

While were at it, can anyone recommend a Gear lube for the rear diff as well? I've been considering ST synthetic.

 

[Colt45ws]

If it goes away in D it might be a slight misalignment of the range selector on the side of the trans. Might try making sure its aligned right. Is this a hydraulic non-electronic trans? If so, might check TV setup and adjustment.
Personally though, I like feeling the shifts. I think them grabbing gears firmly, though not harshly, is better for longevity.

 

[crazyoildude]

maxlife is my choice
I dont know about that 1 to 2 clunk that does not sound good at all

 

[bmwtechguy]

I have the same car/transmission and the shifting does change somewhat between D and OD. In my 300k mile unit, in D it seems to shift a bit more firm overall than in OD. Plus the downshifts as you come to a stop are much more noticeable. It has not been rebuilt.

If I was to change ATF right now, I would definitely pick up some Maxlife from Walmart at 3.69/qt. Best performance/price I have found around here. Local autoparts stores have the same fluid for $5/qt or more.

 

[toyota62]

My experience Any Dex 6 will give you the best shift quality..I use ACDelco.I have tried many many Fully synthetic dexron fluids, POA,Ester base and group3 base but can't beat the Dex 6 shift quality.

 

[bmwtechguy]

And the current Maxlife is "recommended for" Dex VI, BTW.

 

[JHZR2]

Id go with valvoline VI. No need for the "extras" of a maxlife type fluid, IMO.

I flat out do not trust ST products, and would prefer to use fluids from a company that does more than just blend to some spec for bottom-line pricing (though I guess you could make an argument that Ashland is just a blender too). IIRC, their gear oil was recalled or at least found to be deficient in necessary additives, etc. recently.

Ive been running pennzoil Dex VI in my truck (same AT) and have found that it is pretty good too. I think you could consider Pennzoil and castrol Dex VI, both of which Ive seen as readily available, as good options too.

 

[JT1]

I see that nobody has recommended mobil 1 atf, has it fallen out of favor here at BITOG?

 

[crazyoildude]

I did not know wal mart had max life dexron 3

 

[Colt45ws]

Originally Posted By: crazyoildude
I did not know wal mart had max life dexron 3

Some do.

 

[bmwtechguy]

Weird, and they it have priced below all the ST fluids. They also have Maxlife gallons too, but priced so it ends up costing less by the qt. I buy the ML atf qts, needless to say.

 

[ludey]

Originally Posted By: crazyoildude
I did not know wal mart had max life dexron 3


They have mostly Max Life motor oil for most of the Wal-Marts at least in California.

 

[sciphi]

The Max-Life ATF is hard to find. Some WM's have it, others don't. On a recent trip, I scoured 3 WM's to get enough Maxlife ATF to flush my Buick's 4T65. I cleaned out two, and made a good dent in the 3rd.

Also, I ran into a vendor at the second WM who was a giant fan of Maxlife, and helped a fellow traveler on the quest.

 

[jstutz]

I have two 4l60 transmissions and have run generic ST,Coastal, regular valvoline and M1 multifluid and honestly have not noticed a difference between any of them. I have a 4l80 in my suburban and when i changed it to valvoline dex V1 there was a definite shift quality difference vs whatever was in there. This truck had a pretty hard 1st to 2nd gear shift and the dexV1 really helped that out. From limited experience with my three trucks, the only one that i ever noticed a difference with was the Dex 6.

 

[ryan2022]

Originally Posted By: Colt45ws
If it goes away in D it might be a slight misalignment of the range selector on the side of the trans. Might try making sure its aligned right. Is this a hydraulic non-electronic trans? If so, might check TV setup and adjustment.
Personally though, I like feeling the shifts. I think them grabbing gears firmly, though not harshly, is better for longevity.


I agree. Hence the use of shift kits to improve shifting. Better to firmly change gears than to slide into them.

 

[tig1]

Originally Posted By: JT1
I see that nobody has recommended mobil 1 atf, has it fallen out of favor here at BITOG?


Mobil 1 ATF works great in all the Ford transmissions I have put it in. Been using it since the early 90s with smooth up shifts and down shifts, and never a transmission or PS pump failure, yet.

 

[jstutz]

I have used M1 for 175k miles in my blazer until i switched to valvoline dex 6 and transmission still shifts fine. Transmissions are one of those things that i prefer to chage every 30 to 50 K miles so really the fluid i use probably dont matter but i use the synthetic because it makes me feel better knowing i have a good fluid in there. I used to tow a lot with my trucks through the mountains and i dont have a transmission temp monitor so i guess the synthetic was just insurance for me.