Oklahoma Ram Club - T-Stat info for hemi guys

this is not my write up I just copy pasted it cause I found it very interesting and helpful.

Here's some info to help with finding & choosing a 2003-2010 5.7L / 6.1L Hemi low-temp thermostat:

The stock t-stat is a 2-stage design, but it can be replaced with a regular single-stage t-stat. I asked both a Dodge dealer tech and a Hemi hotline tech about using a single-stage stat in a 5.7L or 6.1L Hemi and they both said it would work good and be safe, no potential engine damage.

The downside of a single-stage t-stat is the heater takes longer to warm up.

The port the stat fits in is deep, so either a short or tall stat will fit. The stock gasket is re-usable if the stock t-stat is removed carefully.

T-stats for 1971-1978 Dodge 360-440cid engines will fit 2003-2008 5.7 & 6.1 Hemi's, so you can go to any auto parts store: Autozone, Napa, Carquest, Summit, Jeg's, etc., or performance manufacturers like Milodon, Jet, Mr. Gasket, etc. & ask for a thermostat that fits a 1971-1978 Dodge 360-440cid engine.

These thermostats will fit 2003-2010 5.7 & 6.1 Hemi's:

195*F T-Stats:
Carquest 195*: cq-30239
Summit 195*: sum-360196
Be Cool 195*: bci-78008
Napa 195*: THM-532060

180*F 2-Stage T-Stats:
Jet 180*: JET-10183
Stant 180*: #14168; You will have to grind this t-stat down about 1mm so it will fit right.

180*F T-Stats:
Carquest 180*: cq-30238
Milodon 180*: mil-16406
Mr. Gasket 180*: mrg-4367
Napa 180*: THM-291
Summit brand 180* stat: sum-360181
Mopar 180*: dcc-4876307
Be Cool 180* stat: bci-78007

The 1st low-temp t-stat in my Hemi was a CQ 160*F. I switched from the CQ 160* to a Milodon 160* because the Milodon is better quality: thicker material and better design. A 160* t-stat will throw a P0128 code every few days, so you should not get one unless you have a tuner to read and clear codes. 180* stats usually do not throw codes.

12/30/2006: switched from Milodon 160* to a Milodon 180* because the 160* is too cold. a 180* t-stat is about as low-temp as you can go without causing excessive engine wear. see article:
http://performanceunlimited.co...ons/thermostats.html

If you still want to put a 160*F t-stat in your Hemi after reading the article in the link above, here are some 160*F t-stat Part Numbers:

160*F T-Stats:
Be Cool 160*: bci-78006
Carquest 160*: cq-30236
Milodon 160*: mil-16405
Mr. Gasket 160*: mrg-4366
Napa 160*: THM-191

1/10/2010:
switched to a Jet 180* thermostat: JET-10183 in July '09. My engine ran cooler with the Milodon 180*, but it reaches operating temp quicker with the Jet. I have had NO P0128 codes with the Jet t-stat at all.

for those who don't know, taking too long to warm up will trip a P0128, just like not reaching a high enough temp will throw a P0128.

also, the heater gets warm WAY sooner with the Jet 180*: about 2 miles vs. 5 -6 miles to get the heater warm with the Milodon 180*.

My 2 cents:
a stock-style 2-stage design thermostat is best for a street truck.

single-stage high-flow, balanced-flow design t-stats like Milodon 180*: mil-16406 & Mr. Gasket 180*: mrg-4367 are great for keeping race trucks cool.

side note:
a Diablo or SCT custom tune can be written to tell the PCM that a longer warm-up & lower operating temp are o.k., so a Milodon 180*: mil-16406 or Mr. Gasket 180*: mrg-4367 or Milodon 160*: mil-16405 or Mr. Gasket 160*: mrg-4366 would not cause P0128 codes.