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The old Lesabre trans pan

As I’ve mentioned in other threads, my 05 Lesabre has gotten worse about slipping between shifts, then hard shifting. But to be honest, it’s hit or miss. Sometimes it shifts perfectly. Other times, I think I might not get home. I changed the atf and filter at 150k. Tonight at 170k, I dropped the pan. I have the fluid anyway (a long gone maintenance guy at work stocked up on dex III, yet curiously we run Dodge and Ford service trucks). So here’s the pan. I expected more shavings. Uploading: 20008125-3FA0-47B0-81AB-2463693AE210.jpeg…

The photo didn’t attach properly

There we go. Had to get closer to the house for WiFi.

The magnet had a little sludge. But nothing I’d call abnormal. For all I know, anyway.

Will bolt her back up soon and refill. I wish there was a magic elixir to add. But I’m skeptical of pretty much all additives.

It looked pretty clean to me but what do I know? My magnets were always really fuzzy and gray residue on the pan. I really think you should ad an additive at this point. Might be just sticky solenoids. I don’t remember what the folks here have recommended for an additive but it looks like that Lucas trans tune or something is fairly good. I hate transmissions. Toward the end my Riv would neutral out from 1st to 2nd when it was hot out. The odd thing was it was only once in a while but would several times at the same stop light when I made a particular side trip on the way home. The trans folks didn’t know but seemed to think it was a worn shaft or something that normally is not replaced in an overhaul.

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If I were to add anything to the transmission fluid to stop the slipping. it would be this product.

If it didn’t work with many that miles on the transmission? Time for a replacement transmission/vehicle.


Auto transmissions are a mystery in my experience. Voodoo and clutches.

One of three things are happening. It’s slipping due to worn mechanical components. It’s slipping because passages, solenoids, etc., are clogged. It’s slipping because the electronic solenoids that tell it to engage are…faulty. Voodoo, I say!

I had to replace the solenoid package on the Olds but that just went from drive to 2nd gear limp mode on the freeway all of a sudden. They were evidently a problem in 95. Cost somewhere under $300 plus the tow to the shop.

That is why I liked the old Chrysler Torqueflights with adjustable bands. Good tough transmissions, THe modern 5 to 9 speed transmissions save a lot of fuel though.

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One of the oil change chains near me bought nothing but Dexron in 55 gallon drums, they added an additive pack to supposedly tailor it for other makes. Not on my car you won’t.

I wonder if that was what was happening with your old maintenance guy?

The additives are confusing to me. Are they friction modifiers? Or cleaners/solvents to remove deposits? Or a mixture of both? There are several brands, Trans X, Seafoam, Lucas, etc. My gut tells me the line pressure is low (there’s some pressure sensor that’s commonly flaky but difficult to replace, I’ve read) and I need more friction. I don’t really think the problem is sticking solenoids as the trans is fairly clean, and I doubt it’s hard parts or clutch failure/wear. Is Trans X a friction modifier (increases friction)?

I think I’ll just add fluid and see if there’s an improvement (kinda doubt it). If not, I can pour in the Trans X later…?

I think he worked on private vehicles in his spare time and bought parts and fluids with company funds. I heard that rumor after he left, so who knows.

I’ve heard a lot of (most) trans shops near me that do rebuilds use dex 3 and a friction modifier (lubegard product) rather than buying mfr specific fluids. I’d be a little more comfortable with the mfr branded fluids too, really.

Most of these additives have conditioners that try to soften dried/hard seals within the transmission to restore hydraulic pressures.


There’s usually some test ports on automatic transmissions. These allow the shop to install a pressure gauge. The set of pressure tests taken at the various operating modes helps determine what the problem is. It’s usually the seals are worn allowing the pressures to leak down, which makes it impossible for the actuator to put enough force where it is needed to effect the shift, or the clutches/bands are just plumb worn out. Sometimes putting in fresh fluid will improve the seals enough to get it working again, for a while. Transmission fluid contains seal conditioning chemicals. (At this point on the radio show Tom would be barking like an ocean seal for comedy effect … lol … ) But you could get lucky and the test port pressures will tell the shop the problem is just a faulty solenoid. That pan looks pristine, so luck may be in your path.

John do you have a 4L60 transmission?

On the truck, yes, but this is on the Buick. I think they’re similar. But the Buick has a 4T60e or 4T65 or something like that.

The T stands for transverse where the L stands for longitudinal. So they may be almost the same internally, I do not know.

I spoke last night with a friend who’s a very experienced transmission builder. He told me there are various springs available for the pressure regulating valve that is located after the pump. He said that when doing a rebuild he will always use a heavier spring which increases the transmission line pressure. This produces a more solid clutch engagement, resulting in a longer life for any friction elements.

Ok, thanks.

From what I’ve gathered, you have to remove the trans, or seperate it from the engine, in order to gain access to the pressure control solenoid. I think it’s known to be flaky and controls the pressure to some degree during shifts. At one time, I had a hidden or pending code referring to a longer than expected delay between shifts or something of that nature. That lead me to investigate a bit and the trans pressure control solenoid seems like a likely suspect.

But…If you have to remove the trans (or nearly have to remove it) to gain access to that solenoid (or the springs you referred to), I suppose you’d might as well rebuild it while it’s out since it has 170k miles anyway. I’m assuming that’s what a shop would recommend. Shops I’ve dealt with want you to leave the car, then they’ll tear into the trans to see what’s wrong. Then it’s rebuild time anyway once you’re that far in.

So, I guess I’ll fill it with ATF tonight and see if the new fluid improves anything. Then just ride it out. It’s been slipping between shifts to varying degrees for some time now. Sometimes it shifts perfect, other times it doesn’t. So that randomness puts me in the mind of a solenoid. Maybe it’s clogged partially and the new fluid will help…