[ZLRob]

Originally Posted by radz28

Excellent news, Rob! Like we already discussed - it's been EMPHASIZED to me that correct fluid level is essential for these things. I didn't think an over-fill, like you found, would have as profound effect as you experienced, but I guess it's not a surprise. Thanks for sharing, because this is quite helpful.

Regarding the OP's video: That's a great video and a lot of helpful information. Some comments that come to mind (take them or leave them):

• * Caution anyone looking for upgrades or improvements research their year and model. I'm not finding consistency with some of this stuff, so what we see for a '19 ight not work on a '21, for example
• My car (2020 ZL1 built in 07/19) has an aluminum pan
• My car's thermostat is in the valve body (attached). From my research, and I could be missing something, there is no other thermostat for the tranny in my car. The NGD it I'm installing eliminates the function of the OEM thermostat anyways.
• Make sure if you're replacing that OEM Cooler Line Manifold that there's a thermostat in there. My car's manifold has NO indication of a thermostat in this housing, so if your car has a similar set-up to mine, changing to that by-pass won't help much if the OEM one is still in the VB

You know speaking of the thermostat I really gotta wonder where they are located on 17's like my own. I wonder if they are still in the valve body or if they are in the cooler line or somewhere else entirely. GM went and changed so many things from year to year and have no indication of it apparently, which makes for really annoying and frustrating inspection, service, and repair procedures on these cars.

Also to anyone else reading this, you need to make sure you are at your cars exact operating temp (when your thermostat is set to open) before you pull the plug. For my own 17 it was set to 203 degrees F*. My temp to pull the plug was exactly within this specific range.

For others you may be able to pull it around the 170-180 mark as some of the later Z's ran a cooler thermostat.

It is worth noting that the overfill on mine was making the transmission run a full 4* hotter, because the moment I pulled the standpipe level plug my temp went from 203* to 199* immediately after. I checked these temps immediately after reinstalling the level plug and was surprised by just how much a difference this what otherwise would be considered trivial difference in level made.