Transmission Fluid Advice

truckguy82 · August 6, 2019

Just now, kickass audio said:

I thought it still had a little bit of a bypass for it like the thermostat for the engine. If that's the case I can just take it around for a drive and get it nice and hot and let it rip.

Yeah i think it has a little bypass. I just know whatever is coming out of the trans cooler is dead ambient, not a hint of heat, so it’s pretty slow.

As for getting it real hot, difficult to get it above 200, and it closes at 190. I suppose it’s doable. Would suck so bad if you got any on you though. Thats instant burn.

Also how will you get it back into the cooler?Just refill twice?

kickass audio · August 6, 2019

2 minutes ago, truckguy82 said:

Yeah i think it has a little bypass. I just know whatever is coming out of the trans cooler is dead ambient, not a hint of heat, so it’s pretty slow.

As for getting it real hot, difficult to get it above 200, and it closes at 190. I suppose it’s doable. Would suck so bad if you got any on you though. Thats instant burn.

Also how will you get it back into the cooler?Just refill twice?

If it is slow that's why I change the fluid in the summer when it's around 85 degrees. It is a lot thinner then. For refilling it, I was just going to dump it into the dipstick opening as I am draining it out (thankfully I have a dipstick on the trans unlike most other vehicles that they removed it on).

i'm only at 52k miles without a trans drop or flush and it's not bad. It has a slight color to it but not that dark. It also doesn't smell burnt at all so I have that going in my favor.

truckguy82 · August 6, 2019

6 minutes ago, kickass audio said:

If it is slow that's why I change the fluid in the summer when it's around 85 degrees. It is a lot thinner then. For refilling it, I was just going to dump it into the dipstick opening as I am draining it out (thankfully I have a dipstick on the trans unlike most other vehicles that they removed it on).

i'm only at 52k miles without a trans drop or flush and it's not bad. It has a slight color to it but not that dark. It also doesn't smell burnt at all so I have that going in my favor.

It could potentially take 2 hours to drain fyi, there’s like 13 quarts.

and the fact that your flushing it with fresh stuff figure another 5-10 quarts wasted because of mixing and waiting for it to be clear again

good luck, guess it all depends on how slow that flow is. My educated guess is a trickle

royalkangaroo · August 6, 2019

This is a pretty detailed how-to explanation.

I may just end up doing it myself, definitely not going to do a flush.

kickass audio · August 6, 2019

1 minute ago, royalkangaroo said:

This is a pretty detailed how-to explanation.

I may just end up doing it myself, definitely not going to do a flush.

That's exactly what I was going to try. He never mentioned getting it hot for it to flow better so we might be fine without it being up to operating temp to run it through like in this video.

Beer Belly · August 6, 2019

After reading this, guess I made a boo boo letting the dealer to a Trans Service (45k on the clock), they said it would be a flush $240. Saving grace, 100k / 6 year warranty.....6 years because I bought out my lease and had it certified....got a year added to the drivetrain warranty along with a one year bumper to bumper

truckguy82 · August 6, 2019

12 minutes ago, kickass audio said:

That's exactly what I was going to try. He never mentioned getting it hot for it to flow better so we might be fine without it being up to operating temp to run it through like in this video.

Because he didn’t flush the trans cooler and the lines going to it

The trans thermostat is Bolted on the outside of the transmission, and then the transmission cooler lines are attached to the trans thermostat.

you can bypass the trans cooler by simply unbolting the thermostat

what you cannot do, is just unhook the trans cooler return line and just have the transmission pump the fluid into a bucket

truckguy82 · August 6, 2019

15 minutes ago, Beer Belly said:

After reading this, guess I made a boo boo letting the dealer to a Trans Service (45k on the clock), they said it would be a flush $240. Saving grace, 100k / 6 year warranty.....6 years because I bought out my lease and had it certified....got a year added to the drivetrain warranty along with a one year bumper to bumper

I’ve already pumped my out and replaced it. Did it 3 times out of the dipstick. About 4 quarts each time. It was pretty easy, but I’d much prefer a full flush from the dealer as they somehow get the thermostat open and flush the trans cooler

1SLOW1500 · August 6, 2019

Not all trucks have a thermostat.

Sent from my SM-N960U using Tapatalk

truckguy82 · August 6, 2019

8 minutes ago, 1SLOW1500 said:

Not all trucks have a thermostat.

Sent from my SM-N960U using Tapatalk

That's news to me, I thought every k2xx v8 had a thermostat to the cooler. The only exception being the v6 because it didn't have a cooler.

truckguy82 · August 6, 2019

I guess it would be possible to pump the fluid out from the cooler return line if the trans thermostat impedes flow on the return side.

The trans cooler line input and output go direction into the trans thermostat, which is bolted to the outside of the trans. So if it restricts flow on the supply line to the trans cooler then you could not simply unhook a cooler line and have it spill out. If it restricts flow on the return side, you actually could.

I suppose I always assumed it restricts the supply side, or both sides potentially

royalkangaroo · August 6, 2019

1 hour ago, Beer Belly said:

After reading this, guess I made a boo boo letting the dealer to a Trans Service (45k on the clock), they said it would be a flush $240. Saving grace, 100k / 6 year warranty.....6 years because I bought out my lease and had it certified....got a year added to the drivetrain warranty along with a one year bumper to bumper

I wouldn’t call it a boo boo if you didn’t have any problems following. I would just think your next service would be a pan drop to get the filter changed.

M-Wheeler · August 6, 2019

By a new thermostat from dealer $75

Perform the thermostat delete mod on new thermostat

Remove current thermostat, (keep for later if needed for colder weather, takes 5 minutes to swap)

Install modified thermostat

Now you can flush system using outlet line of thermostat

Refill using the newly updated Mobil 1 Synthetic LV ATF HP fluid (12 qts).

Smooth as butter, no jerking, no hesitant shifting.

sk · August 6, 2019

Just FYI -- GM now calls for an updated fluid. I don't remember all the specifics but it's supposed to help with the "shift jerkiness" of these transmissions. The TSB just came out a few weeks ago. Supposedly the bottles are similar but the dealers were given detailed info on which fluid to use and how to get rid of any remaining inventory of the previous fluid.

Here is the info:

https://gm-techlink.com/?p=11127

Edited August 6, 2019 by sk

M-Wheeler · August 6, 2019

9 minutes ago, sk said:

Just FYI -- GM now calls for an updated fluid. I don't remember all the specifics but it's supposed to help with the "shift jerkiness" of these transmissions. The TSB just came out a few weeks ago. Supposedly the bottles are similar but the dealers were given detailed info on which fluid to use and how to get rid of any remaining inventory of the previous fluid.

Here is the info:

https://gm-techlink.com/?p=11127

Ummm...same stuff as I just posted above.