2015 Hemi in Florida how cool is too cool?

[FLA1500]

First Post Appreciate the Advice - (search didnt yield an exact answer so trying a first post)

2015 Hemi with 86K. Has been maintained but in the last 9 months since i got it from a family member i have been going through and cleaning out and changing every fluid and upgrade were it makes sense.

Before i started my water would fluctuate between 203 and 212 (no load)
Trans would alternate between 195 and 210
Oil would lock in at 52-53 psi at idle to a warm 45-46 and would heat up to 212-218

I serviced the tranny added the B+M aluminum +1 and put Mopar fluid back in.
I also removed the coolant heat up loop with a kit so the tranny always goes through the cooler.
This service (aluminum pan, +1 QT, fresh fluid, and cooler bypass removal) lowered my tranny to 165-170.

This past weekend my water pump gave out completely. I replaced it with a gates unit, and put a 180 thermostat in as well as doing a complete purple 10 year 150K OAT purple coolant flush. It had a pinkish cooler prior i think the 100K mopar and it had been serviced once prior in 2022-2023.

My water temp now is 180-185 tops and my oil never got above 200. My tranny also dropped down to 140-150 degrees. SO everything dropped another 15-20 degrees.

Ambient air here is 65 degrees FYI, heat etc works great, i live in Southern Fla.

My question is - is this too cool should i go back to the 195 (really 203) thermostat and bring my temps up a little. Is 135-150 too cold for the tranny or am i just protecting everything. I am trying to keep everything cool and have always felt like heat was the enemy as well as not servicing fluids. Everything feels fine with shifting etc. The engine gets to temp quickly it just stays at 180-185 coolant and is keeping the tranny about 15 cooler than it used to be.

I change the oil 2x a year at around 4K on it with Valvoline Restore and Protect 5w30 so i dont think water/ moisture is going to be that bad even with the cooler temp. No plans on towing or putting under load FYI.

Thanks for the advice.

 

[EdGs]

I also have a '15 Hemi (SLT QC 2WD 8SPD 3.21) and live in SWFL.

Recently did a cam/lifter job, unhooked and blew out the transmission cooler lines, and installed a 192° tstat.

I have a PPE trans pan and @caulk04's trans tstat bypass, but have not installed them yet.

My trans temp is much cooler longer now. It will still reach 180° -190°, but takes a good bit to get there.

My coolant temps for the most part hover 198° - 204°, but occaisionally get to 215° - 220°, but I don't know why.....

208K miles, btw.

I personally like the lower temps, and if you aren't having issues with the 180° tstat, IMO I would leave it alone.

Sounds like you have a sweet, low mileage ride, and are giving her the love she needs.

 

[Daw14]

I’m in south Florida also, I would wait till this cool spell is gone , before swapping that t-stat.
Give it another try when we are back in the upper 80s.

 

[ramman95]

I also have a 2015 1500 with the 5.7L. In the summer, with the OEM 203° thermostat my coolant temperature would get up to 220 before the electric fan would come on, and cool it down to around 200. IMO, that's a little bit too high. So I replaced the thermostat with a 180°. For the rest of the summer, that was perfect, it would run around 195, i don't think it ever went over 200. Come winter in NJ, it would barely get over 180. Even though I had decent heat, that's a little too cool IMO. So I installed a 192° thermostat and it's been perfect, it stays between 190 and 195. I'll leave it in there and see how it does in the summer. The good thing about these trucks is that it literally takes 5 minutes to replace the thermostat, and you can reuse the rubber gasket.

 

[caulk04]

You're golden, no worries with any of that.