Repair-It

billgiacheri wrote:You have definitely miss-quoted me a couple times here:

High-pressure air is automatically injected into the fluid stream adding agitation to the ATF oil to enhance the removal of contaminated ATF oil and debris.

This is bad because it can potentially get debris stuck in places it shouldn't go, not because it is getting it all out.

I don't think this is an issue. Internal valves and orifices can see up to full pump pressure which is like twice what shop air is.

GM themselves is not a believer in that old wives tale of needing to keep junk inside various valves and orifices because, somehow, that junk is holding the transmission together.

Nobody said the junk was holding the transmission together, but that the friction material from the trans clutches being in the fluid helped the clutches with friction. That friction material is not present after a flush, causing the trans to slip more.

Transmission fluid has specific friction modifier additives for this specific purpose.

But that doesn't even matter - there is no note in here that says "when the fluid has been in the transmission more than X miles, do not service.". I just find that ridiculous.

In the case of your Corolla I think the advice was more like "I don't want to tell him to service it and then blame me if symptoms develop.". If I was keeping the car I definitely would have serviced it.

GM themselves is not a believer in that old wives tale of needing to keep junk inside various valves and orifices because, somehow, that junk is holding the transmission together.

Nobody said the junk was holding the transmission together, but that the friction material from the trans clutches being in the fluid helped the clutches with friction. That friction material is not present after a flush, causing the trans to slip more.

Transmission fluid has specific friction modifier additives for this specific purpose.

But that doesn't even matter - there is no note in here that says "when the fluid has been in the transmission more than X miles, do not service.". I just find that ridiculous.

This "old wives tale" is from a time of inferior transmission fluid <edit> and transmissions </edit>. There are plenty of anecdotes of someone's uncle 45k mile Hydramatic (Dextron) who decided to change the fluid then had the trans fail 600 miles later. That's why they never change the fluid in their newer TH350 (Dextron II/III) even when they get to 100k miles. They are of course forgetting about the fact that the "new" transmission/fluid is a much better unit with a longer life expectancy so it appears that it holds together because they didn't change the fluid rather than it holds together because it is a more durable unit with a longer service life.

DEXRON.

https://en.m.wikipedia.org/wiki/DEXRON

/pedantic

LOL

DEXRON

The original Dexron fluid, like its predecessor Type-A/Suffix-A, used sperm whale oil as a friction modifier. The U.S. Endangered Species Act banned the import of sperm whale oil, so the fluid had to be reformulated

There you go. You don't want to mix your old and new sperm whale oils.

In all seriousness there is quite a bit of evolution to transmission fluid.

Alright we got a little off track there.

I drove the car again today and I will say again, the transmission does shift even better than before for sure. I have to attend to the Ram first but I'd like to run another 5+ quarts through this 5L50 and get my Dexron-VI levels up to 75%+.

Finally took it on the highway. I think it actually has improved. This is a good sign.

I did another drain and refill. Unfortunately without taking the pan off, not as much fluid came out. I probably only used 4 quarts. Still my math tells me I have changed 75% of my fluid. I have not road tested yet. I did not add the additive, because it doesn't seem to need it.

I was showing Bill the Tech 2 today. I went into the transmission stuff and saw that the transmission fluid had 10% life left. Of course, this is because it was never reset, because it is only accessible via Tech 2 (why??). So since I did all the fluid changes, I decided to reset it. But you don't just have to reset it, you can also reset it to any value you want. So I set it to 95%. How cool is that?

That is very cool! How does it estimate life? Is it similar to oil life?

It must work like oil life. Number of shifts, load during shifts (i.e. WOT), trans temp. I should see what my FSM says.

My brother in law's 04 SRX actually has the trans life exposed in the DIC and he can reset it. Apparently after 2004 GM just got rid of this (Jamie's 08 does not have it and neither does my 05 STS). Makes me wonder what the GM CONOPS is...I mean does the car indicate something when the life gets lower than 10%? If you have to plug in a Tech 2 to see it, I don't know if that is super useful to the end user, especially since just about all of these cars will be at least on the second owner by the time the life gets down there. Only the ignorant would bring an out of warranty luxury car to a dealer for service.

The trans has been performing perfectly though I know there is still like 25% of the old nasty Dexron III in there and it would be nice to get rid of it.