Seafoam Trans Tune is good stuff!

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My Cadillac CTS (5L40-E trans) has a little over 115k miles, and the auto trans has been getting better over the past two years since I bought the car. Specifically, it had what I called loopy, or otherwise erratic shifts, which were worse when the trans fluid was cold (much like the symptoms of low ATF level, but I verified the level was fine). I don't know if these are actual "transmission flares" but they consisted of a surge feeling upon upshifts, and inconsistent or oddly timed upshifts while coasting or light pedal. My first thought was that this issue was caused by the high mileage, but I also noticed it in my friend's Ford Focus with 45k miles. My first approach was to have the ATF replaced at a local shop (they probably used NAPA Dexron VI, given the shop's affiliation). The shifts did not change, so I dropped the pan, replaced the filter, and replaced the lost fluid with Valvoline Dexron VI. The shifting improved a little, but was not what I considered normal. My next step was to add a bottle of Lubegard red. The upshifts became smooth and normal during acceleration, but the weird coasting/light acceleration issues remained. It was almost as if the car was trying to get to the highest possible gear, regardless of whether it was time to do so. In other words, if i accelerated to the point of a downshift, and then backed off around 2500 or 3000 rpm, it would shift back up, and then immediately shift up again, only to shift back down to maintain around 1500-1800 rpm cruising. After about 4 months since Lubegard, this issue hasn't changed at all. Today I decided to try Seafoam Trans Tune, which I had used previously in my power steering fluid (with little to no effect on steering performance; however, a friend in college successfully used it to fix a slipping trans). I suspected the outcome would be A) trans tune would do nothing, B) trans tune would completely solve the shifting problem, C) trans tune would completely F up my trans, or D) trans tune would cause ATF to leak all over my garage. The preferred outcome is B, but A would be acceptable. C or D would be bad. I am happy to say that Trans Tune was effective within a few miles, and the trans now shifts great during acceleration and cruising! I haven't tried it with cold starts yet, but I am optimitic. I will update this thread in a few weeks with any changes to the shifts, etc.
 
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Gotta be a believer sometimes. My sons 95 Geo Tracker had a notorious no shift out of first issue. 185000 miles. Thought it was done for. Used mighty vac thru the fill tube, sucked out all the Aunt Jamima syrup I could. Refill with Valvoline dexIII and Seafoam trans. Slow drive around town and a day later shifts like new. Didnt feel like dropping driveshaft to change filter. Probably do the same routine before winter and hope for Spring.
 

RyanY

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Originally Posted By: Warstud
Did you use the whole can?
I added about 3/4 can and spilled the rest while maneuvering my pump under the car.
 
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Interesting. Please keep us posted how things work out. Keep an eye on the output shaft seals for weeping, though that is relatively low miles and it has gotten a few fluid changes so those kind of leaks are less likely. Watch for your fluid getting noticeably darker if the Trans Tune dissolves and suspends some stuff. Consider an early fluid (and filter, if applicable) change in maybe a few thousand miles to get some of the junk out of the system instead of having it float around for the next 30k+. At the next drain and fill, perhaps try Valvoline Maxlife high mileage ATF. Many people including me had good luck with that stuff smoothing out sloppy transmissions. I've also used Trans Tune as part of a power steering flush to get some really gross old fluid out, and left in a small amount as cleaner when I refilled the system. No leaks or issues there 16k later (knock on wood).
 
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It is a great product and got my old transmission working great again where other products did nothing.
 
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Originally Posted By: VeryNoisyPoet
Interesting. Please keep us posted how things work out. Keep an eye on the output shaft seals for weeping, though that is relatively low miles and it has gotten a few fluid changes so those kind of leaks are less likely. Watch for your fluid getting noticeably darker if the Trans Tune dissolves and suspends some stuff. Consider an early fluid (and filter, if applicable) change in maybe a few thousand miles to get some of the junk out of the system instead of having it float around for the next 30k+. At the next drain and fill, perhaps try Valvoline Maxlife high mileage ATF. Many people including me had good luck with that stuff smoothing out sloppy transmissions. I've also used Trans Tune as part of a power steering flush to get some really gross old fluid out, and left in a small amount as cleaner when I refilled the system. No leaks or issues there 16k later (knock on wood).
Good advise.
 
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Glad your happy with the results you've gotten; it's always prudent to have clean fluid in the transmission. If you haven't, you might want to check for any transmission-related TSBs for your vehicle--there may be a transmission software reflash that would further help resolve shifting issues.
 

RyanY

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Originally Posted By: khittner
Glad your happy with the results you've gotten; it's always prudent to have clean fluid in the transmission. If you haven't, you might want to check for any transmission-related TSBs for your vehicle--there may be a transmission software reflash that would further help resolve shifting issues.
That's a great idea. I did the relearn procedure but have not reflashed. I will see what I can find...
 
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It's a computer controlled transmission. All the hydraulic solenoid commands are based on speeds and input power (throttle position). It's difficult to understand how a transmission additive modifies the shift schedule.
 
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Many times electronic transmission woes can be “fixed” for a long time by a fluid change and clearing the adaptive learned values. When you wipe the adaptive values clean, either with a factory scan tool or by crossing the battery cables together ( with them disconnected from the battery of course) the transmission controller will now have to learn “how to walk” again. Crossing the battery terminals with a jumper wire simply speeds the reset process up. ECU memory is written to the ROM magnetically. It takes quite a while for the magnetism to dissipate, so if you give it a place to go it expedites the process. Many people believe that memory is written in capacitors, and once you disconnect the battery the memory is wiped. This is not true. It still takes at least 10 minutes for the memory to clear with the open ends of the battery cables touching each other, and much longer (hours) if you only disconnect the battery. I feel you may have finally actually cleared your adaptive values, and once the trans controller finally learns the excessive clearance in the clutch packs again you may be back to goofy shifts. I could be wrong, just be cautiously optimistic. I have never seen a solvent or viscosity modifier actually repair a transmission that had an actual mechanical problem, whether it be worn clutches or simply excessive clutch pack clearance. I hope for the best with yours, but adaptive values take many Drive cycles to settle in to normal. So report back after 500 to 1,000 miles. If it’s still acting like you believe it should, then you did accomplish something.
 

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I realize the addition of a cleaner like trans tune is unlikely to reprogram the shift parameters, or to repair any damage to mechanical parts. Hence the reason for my skepticism before i tried it. However, the weird surging during shifts was certainly not normal, and had become particularly annoying over the past few years. ATF and filter replacement, as well as lubegard additive, failed to eliminate the problem. The cruising rpm is still around 1500-1800, just as it was before the trans tune. It just gets there more smoothly now, without the up/down rpm jumps and surges. Could the smoother shifts result from cleaner solenoids, valves, etc, as suggested by the Seafoam site? I don't know, but the shifts are certainly better (for now, at least). I hope it lasts, but only time will tell.
 
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The surging could be attributed to a torque converter shudder. Most all lock up torque converters these days are not simply on or off, they are pulse width modulated. This, under normal circumstances, eases the transition into converter lockup, and many trans controllers will command converter lockup in more than just overdrive. Some will use the lockup clutch in the torque converter in multiple gears. Usually the 1:1 gear and overdrive. Is it possible that you had been experiencing a converter shudder? New fluid can and will fix this, as the converter clutch is small and weak and doesn’t put up with much abuse. If the friction modifiers in the fluid are torn up, the converter clutch will not be able to engage smoothly.
 

RyanY

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Originally Posted By: 69Torino
The surging could be attributed to a torque converter shudder. Most all lock up torque converters these days are not simply on or off, they are pulse width modulated. This, under normal circumstances, eases the transition into converter lockup, and many trans controllers will command converter lockup in more than just overdrive. Some will use the lockup clutch in the torque converter in multiple gears. Usually the 1:1 gear and overdrive. Is it possible that you had been experiencing a converter shudder? New fluid can and will fix this, as the converter clutch is small and weak and doesn’t put up with much abuse. If the friction modifiers in the fluid are torn up, the converter clutch will not be able to engage smoothly.
This is a reasonable explanation for the improvement after trans tune. However, I wouldn't call the shift issues a shudder. At least, they were nothing like the ones I have seen on youtube. It is possible that the TC clutch was causing the problem though...perhaps a mild version of shudder (?). I was under the impression that new ATF & filter is the best fix for shudder, but that alone produced little improvement over the subsequent few thousand miles. Lubegard also had marginal benefit over another 1k or so. I therefore doubt that the loss of friction modifiers was the cause. At this point I assume something was cleaned, but I don't know what! It still shifted smoothly yesterday...still hopeful that it will last!
 

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Update on trans tune and shifting issues. I finally got around to replacing the ATF, now that the trans tune has had plenty of miles to clean the trans or otherwise work its magic (about 1.5k). I'm happy to report that the initial shift improvement after adding trans tune continued throughout its use. The shifts were still slightly abnormal, but much better than before adding trans tune (dex VI + Lubegard). I now have Maxlife with no extras, and the shifts are better than with dex VI + Lubegard + trans tune, and what I would consider normal. Overall, I think trans tune is a great product that can improve shifts in some conditions, possibly by providing additional cleaning of various components. However, replacing the atf with Maxlife provided the greatest improvement. It is possible that my problems would have been solved by using Maxlife the first time (instead of dex VI), but I have no way of knowing this. Regardless, trans tune was worth the $ and I would definitely use it again, either as a pre-flush cleaner or just to improve shifting.
 
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