Transmission Drain and fill, to pin or not to pin…

I’m doing a drain and fill in my 17’, I’ve read/watched a lot on this and out of left field I saw one of the procedures pinned open the thermostat, got to temp then checked the standpipe. Is this correct or should the thermostat be left closed during the ATF fluid check procedure? Thanks in advance.

 

Pinned open...

 

When in doubt, pin it. It’s kinda like “when in doubt, throttle out.” Good advice, really.

 

I had it pinned open when I installed a trans cooler and did a drain and fill. I took out the pin after the fluid level check was done.

 

Pin in during the warm up and check procedure, pin out once you’re done

or maybe you want to leave it in if you’re s/c’ed or tow a lot

 

Yeah +2 on Leaving it Pinned in year round - only get about 2 cold days a year in central Tx.

 

Leave it pinned after you’re done

 

OPs username is Permafrost. He may not want to leave his pinned all the time…

 

I would leave it pinned open. I put the WAT valve body in along with the deep pan and left mine pinned. Trans temp runs between 185 and 195 in 90+ degree weather.

 

Where do you live? I have mine pinned In cali, the hottest I’ve gotten is 185, most of the time it’s 175.

 

I am in AL. Plus I have a DCLB truck that is lifted and on 35s. Probably more weight, plus other mods.