99 4l60e change to Dexron VI troubles

[99TA]

I wanted to change from Dex III H to Dexron VI...so i pumped out the pan once and refilled with 4 qts Dex VI.Trans seemed to work ok but the shifting felt a little different.We drive it a few 100 miles and i pumped out the pan again abnd refilled it then drove it a few 100 more miles and it startied working very nice.Solid shifts and very consistant shifts.I figured i'd change the fluid out one more time but the last time i had the pan pulled off,installed a new GM factory filter(to replace the Champ labs after market filter installed @ 50k)and refilled with Dexron VI.The pan was perfectly clean and looked like brand new...so did the filter.
Now the transmission acts very strange,its shifts very weak.1-2 shift is ok but weak...2-3 you can barely feel at all and 3-4 the same way.Before i changed the fluid the trans worked perfectly,hard shifts in all gears.Now if you try WOT throttle the trans doesn't slip nbut it shifts so weak its a joke.Almost like a luxury car would.I also notice the car seems to accelerate smoother and a little faster,i'm assuming because the DEx VI is so much thinner than the Dex III.I hope it doesn't ruin anything but tomorrow i'm pumping out the Dex VI and putting back in 4 qts of Dex III.If it doesn't fix it i'm going to be a very unhappy.

 

[onion]

Dex VI didn't cause the problem you're describing. I suspect that you've either screwed up the seal, and the filter is sucking air... or there's something wrong with the filter. Either way, you need to pull the pan back off and see what's going on.

 

[99TA]

i'm getting [censored] off thinking about the mess!Wish i never touched it!I didn't do the work.....i'm really getting stressed out over this!I would think if it was sucking air at the seal the pump would be noisy.Its quiet and goes in gear right away cold or hot.

 

[99TA]

I looked at the viscosity of the Dex VI and Dex III,there is a huge differeance.I'm thinking changing out the last 4 qts just thinned the fluid out that much and changed the calibration.You would think using a thinner fluid the trans would need a different tune to shift properly???I'm going to pull 4 qts out and put 4 qts of Dex III in before dropping the pan.If i'm right the shifting should improve as soon as i do.I tried a pour test comparing the two fluids and there is a huge differeance.The dex VI is very thin compared to the Dex III when you try pouring.That has to effect the shifts in some way.Any engineers on the board here care to throw me some info on this? Please feel free to comment.TY

 

[Brett Miller]

One very important thing to check is the seal where the filter meets the valve body. You did change it, didn't you?

 

[Whitewolf]

Onion is right it's not the change of fluid that's the problem. I'm agreeing with Brett that the problem is something to do with the filter change. If it's sucking air there will be line pressure instability that will affect the shifts.
A comment about viscosity because I have had this question many times before. Yes, new DEXRON-VI is much 'thinner' than new DEXRON-III was, but it is also much more shear stable, so although the new DEXRON-VI is 'thinner' (KV@100C 6.0 cSt) it will remain above 5.0 cSt wheras the majority of DEXRON-III fluids would shear down to about KV 100C 4.2 by about 80K miles. The reason that I am saying this is to point out that since the transmission will work with a sheared fluid of say 4.5 cSt then the difference in viscosity between DEXRON-VI and the former DEXRON-III is clearly not the root cause of the problem.

 

[WishIhadatruck]

I did a 12 Qt. cooler line flush with Dex VI on my '96 Wagon with a 4L60E and I couldn't tell a difference at all in performance. I dropped the pan and changed the filter with a GM filter immediately prior to the flush. I find it hard to believe the Dex VI is a problem. Are you sure it isn't actually working properly now but just doesn't feel like you prefer it?

 

[99TA]

Originally Posted By: WishIhadatruck
I did a 12 Qt. cooler line flush with Dex VI on my '96 Wagon with a 4L60E and I couldn't tell a difference at all in performance. I dropped the pan and changed the filter with a GM filter immediately prior to the flush. I find it hard to believe the Dex VI is a problem. Are you sure it isn't actually working properly now but just doesn't feel like you prefer it?
I think thats it...it feels so different.It actually shifts faster now but it feels like with less force.It seems with the 8qts Dex VI and 4 qts??? Dex III that was left in trans after the second pumping out it worked the best.This last change just changed it so much.I'm ging to pump out 4qts of the VI and add 4 Dex III

 

[unDummy]

If its shifting faster with less force, what are you complaining about???

Viscosity is NOT the cause of your issue.
Filter install is highly suspect here.

DexronVI is a smoother shifting ATF. But, if the shift is fast, and the tranny does NOT slip hopelessly, then enjoy your longer lasting transmission.

If you want a more demanding shift, program or shift-kit it.

 

[99TA]

It helped adding the dexIII but its still not right.I don't beleive the filter or seal is the problem because the fulid is completely clear,no signs of aeration and the pump is quiet.If it was sucking any air in the fluid would look bubbly and foamy with some type of pump whine or growl.I'm thinking the electronic pressure regulator might be worn badly,i know they are trouble in these trans because gm didn't use a hardened seat in the regulator.I just think its odd all i do is upgrade the fluid and now its shifts completly different.I might just suck the all the fluid out and go back to dex III.I don't think its going to harm anything etc,but who wants to drive a LS1 TA that shifts like its a luxury car.It has absolutely no feel to the shifts at all,if the tach didn't drop i'd never know it shifted into 4th and 3rd is weak too.It goes to shift but laggs then softly goes into the next gear.Very odd,i don't like it.Maybe its just showing its age but it did work nice before the 3rd 4 qts of DEX VI were added.Maybe it cleaned something??? i'm done with it at this point,the more i fuss over it the worse it gets.

 

[Whitewolf]

I think this is one of the comments that I put in yesterday which got lost in the 'crash'. Anyway, here we go again!

The point I was making is that DEXRON-VI has a slightly higher overall friction level than DEXRON-III. It also has an 'improved' friction characteristic so that the curve is much smoother. One of the problems with DEXRON-III fluids was that as they degraded, they tended to develop a 'rooster tail' (that's a situation where the static friction tends to rise relative to the dynamic friction). The effect of this is to give an increasingly harsh shift and it's also bad for TCC shudder. DEXRON-VI is designed not to do that and also to be more fricitonally durable. I think that what you might be observing is the difference between the feel of a degraded DEXRON-III compared to a new DEXRON-VI. There is no difference between the two in terms of shift time, it's just an improvement to avoid harshness, degradation and, therefore, to improve durability.

 

[99TA]

I took it to the trans shop today,he says noway that seal is leaking he has changed 100's of these filters and NEVER changes the seal unless the filter goes into the seal easy.Mine went in hard.He says without a doubt its the change from dexIII to dexVI.I'm going to drive it like it is.I also looked around the net and found quite a few other guys who changed over to dexVI that experianced the same thing,sopfrter smoother shifts.So i'm not concerned about it.Also another thing it no longer does is before the dexVI when you started cold the car would lurch foward in park.Now it just starts without moving,thats telling me there is a huge differeance in the two oils lubricity.

 

[99TA]

I need to add something to this thread so others don't think the dexVI is evil or trouble.The trans works MUCH smoother than it ever did with the dexIII,thats what is so strange about it because its almost like i have a different transmission.I certainly like the fact it comes to a very smooth stop without clunking into 1st gear every time.It seems to accelerate better also.Adding 4 qts dexIII back into the trans did stiffen up the shift a bit.Personally i think the mix i would use for a older 4l60e is 2/3s DexVI and 1/3 DexIII overall.This seems to give the best result for me.

 

[elric]

I changed to Dexron VI in a 1997 4L60E and the result has been great for 15,000 + miles.

 

[Cutehumor]

I've seen several posts on this site where folks are over maintaining their vehicles and end up screwing something up. Since you didn't do the work, everything was fine the previous dex VI changes. I say the filter change wasn't done right.

 

[99TA]

Please no more "the filter is bad or installed wrong posts!I heard enough!save it for the next guy!

 

[99TA]

Originally Posted By: Whitewolf

One of the problems with DEXRON-III fluids was that as they degraded, they tended to develop a 'rooster tail' (that's a situation where the static friction tends to rise relative to the dynamic friction). The effect of this is to give an increasingly harsh shift and it's also bad for TCC shudder. DEXRON-VI is designed not to do that and also to be more fricitonally durable. I think that what you might be observing is the difference between the feel of a degraded DEXRON-III compared to a new DEXRON-VI.
Thats exactly what i'm feeling!The trans is so smooth now its just weird.If the filter or seal was damaged that new fluid would be FRIED already and trans damaged after 100's of miles of driving and a bunch of WOT runs its fine and fluid looks good.I had someone warn me about changing to DexVI just because of the differeance in shifting and clutch durability.He said in a performance car the DexIII was better because it let the clutches slip less on WOT shifts.I suspect one other problem my have come into play here.The presuure reg valve in the pump assembly in the trans are know to be sticky and trouble,the DEXVI may have loosened this valve up or dislodged dirt or debrie in that circuit.The symtoms of that valve bsticking are hard up shifts at part throttle and hard down shifts coming to a stop.Thats exactly what it had before this DexVI change along with a lurch forward in park as you started the car cold.I also notice it went into gear faster with the DexIII.Its just tad slower going in with the DexVI.

 

[gregmp]

I stuck with Dex.III for my 2000 LS1 4l60e. The shifts with Dex.III do get a little inconsistant after 15kmiles of hard driving...so that's when I change/fluid exchange it. I just did the change and the shifting is like new again. Firm but not harsh or abrupt. For $2 a bottle for Penzoil Dex.III, I'll just do service every 15k. Clutch slippage has destroyed quite a few drag raced LS1's, a bit more clutch slippage with Dex.VI is not a good thing.

For a normally driven car the Dex VI is probabbly better for long service intervals, but I'm not so sure the rooster tail at the end of the dynamic friction curve is a bad thing (meaning it's a good thing) for saving clutches.

 

[99TA]

The trans was serviced at 50k,the filter was very dirty the oil looked clean.Refilled with DexIII and driven to 105k,this time the filter was very clean and so was the oil.I have no idea why i switched to DexVI other than i like the idea of never changing it.I'm thinking i may end up with a 50/50 mix DexIII/DexVI.Without any doubt the DexVI completely changes how the trans operates and feels,the car feels smooth like new again.I read someplace out on the net the DexVI acutally lets the clutches slip less?????? at least thats the data logged by a guy testing it in his LS1 car monitering the data output from the trans.It actually shifted faster with less slipage.

 

[Whitewolf]

The clutches do not slip more with DEXRON-VI. Whoever told you that doesn't know what they are talking about!

The shift times are the same with both fluids which is why DEXRON-VI is a drop in requiring no calibration change. The main difference is that the friction system in DEXRON-VI is more durable so it remains consistant for much longer.

Mixing the fluids together is a bad idea because in doing so you throw away a good deal of the DEXRON-VI performance advantage. What it basically amounts to is diluting the DEXRON-VI with an inferior product in which case you may as well not bother.