4T60-E

[knockknock]

Great site, this seems like the equivalent to GM as Allpar.com is to Chrysler...

Anyway, I read a thread on AutomotiveForums saying that replacing the fluid in the 4T60 is a bad idea and can potentially ruin the transmission. Reason: new fluid is "grippier" than old fluid, and will overload the friction plates, having them basically come apart and essentially ruin the transmission.

I used to have a '95 Lumina and did that work at 80K, and sure enough lost the tranny at around 120. Now I have a '99 (lost the '95 in an accident), and the car has about 90K on it, and I was about to change the filter and fluid until I read that...

What is your take on it?

[IsaacHayes]

I belive the deal is the new fluid can disolve any sludge on the clutches, and that sludge is holding friction material, and after that's gone, there isn't a lot of friction materail left in the clutches, and so it slips.

I changed mine at 120k because it wasn't engaging when cold (winter). I droped the pan and filter. Then I did a full flush. It improved shifting, but the cold slipping problme was there until it warmed up. I then put in some GM seal conditioner, and the transmision acts like it's new.

So I don't know what to tell you, but if it's working fine, I'd leave it alone unless the fluid is really nasty and burnt smelling, but then, your trans probably is on the way out then anyways....

I only flushed mine to try and solve problems, and later found the seal conditioner that sovled my problem.

[TurboGTU]

IF its still red...don't bother replacing it.
IF its black or smells burnt...its too late for anything.

If its brown..I would change it with regular Dex II-III. WHen its brown..it already lost its voscocity, and other agents, meaning its like gas, this is not good for the bearings and valvebody, and other moving parts. If its slips..oh well..it was gone anyway. Atleast you'll be able to just have clutches replace..instead of all the moving parts in the trans.

This is especially true if you have a electronic trans which has small filters in the valve body..if the fluid is dirty/worn...and nothing is done to it...thise filters can clog up.
No Dex-IV or sythetic stuff.

[knockknock]

Thanks for the replies, guys.

[sharkey]

its best to change the fluid every 50k km (30k miles) before it starts to break down, or more often under extreme conditions. when the fluid starts to break down, it loses it lube properties and also runs hotter, causing premature wear. yes the new fluid will pick up more particals but its not going to "pack off" with all the friction material off the clutches.

change the fluid in it, you will do way more damage by not changing it.

[tractorman]

I gotta agree with sharkey here. IMO, you're always better off with new fluid. If things are bad enough that new fluid is gonna down the car... then it wouldn't have held long anyway.

When I buy a car, two of the first modifications I make are a drain plug in the transmission oil pan and a trans. cooler. I change the trans. oil around 25K or thereabouts. It's probably more than neccesary, but oil is cheap and easy to change, unlike a transmission.

[sharkey]

the key is keeping the fluid from breaking down. im not big on drainplugs due to the fact that if you just drain the oil, you dont change the filter or get the chance to inspect the pan.

[3400-95-Modified]

yes but a drain plug makes it way easier to get the fluid out to go in the trans to do the filter... damn 4t60e pan is a half acre wide, I dont have many drain catch pans that big. I always leave a puddle.

[PCGUY112887]

If I ever pull the cover on my tranny again i'm going to install a plug for the simple fact that I decided to change the fluid on a windy day, and when part of the pan hangin and fluid was goin everywhere (not all into the catchpan), a gust of wind blew fluid EVERYWHERE, all over my face, all over everything.

[knockknock]

Damn, didn't think draining was that messy. didn't have too much of a problem on the old one :P

Yeah, I think I'll just take my chances and service the tranny on this car. makes sense that if new fluid will ruin it, it wouldn't have lasted much longer anyway.

[napatiger]

when i got my reman trans, they insisted I put Moble 1 synthetic, or I would void the warrenty.
maybe only a good idea if a NEW trans.....

[PCGUY112887]

Mobile 1 makes a synthetic tranny fluid?

[TurboGTU]

Only trans I ever used Synthetic was on Ford AXOD trans since the Pistons had a tendency to stick due to bad workmanship on fords part.

Many people don't like it like me and some 4t65-e guys due to it no holding the clutches. IT will run cooler..but it will slip with high power.

I don't know why not using ONLY Mobil 1 on the trans would void the warrenty. Thats total BS. GM calls for DexIII or equivlent.

ONly fluid specific trans are the Chrysler, Honda, Older ford, newer ford.

[sharkey]

actualy everything newer is going to their own specific fluid. mitsubishi needs its own, chrysler atf+4 goes in the newewr stuff, ford torqueshift trannys need a special fluid. same with vw, mercedies, bmw. even gm is now updating to dextron 6, however that fuid will be replacing dextron 3.