I am seeing around 190* on the highway around 75 mph.
Is this normal or high?

It also drop about 20* in stop and go traffic.

I am reading the factory temp sensor on the valve body.
Also I have a decently sized plate and fin style cooler routed before the radiator heat exchanger.

Im thinking about upgrading to a larger cooler if response is that 190* is high.

 

Install on return line after radiator cooler or bypass radiator cooler.

 

If you want to get technical, that temp is pretty much perfect for fluid life. Anywhere from 170-200 degree's is the ideal temp for transmission fluid on a "life" standpoint.

A larger cooler that doesn't use the radiator should drop those temps 20+ all over atleast and should still get the fluid plenty warm to allow it to do it job well.

 

If I'm in heavy traffic, mine is around 175-190 in stop and go. On the freeway, my temps is about 130 cruising at 75

 

This ^^^ pretty much all sources report you aren't in danger until you start approaching 220° F or so.

Richard

 

as long as i'm below 200*, i'm happy.

 

It sounds like the converter isn't locking if you are that hot on the highway.

 

I would be thinking if i was 190 on the highway. here in buffalo it only gets into the 90s a couple times a summer and the roads are fairly flat. 190 seems high to me for no trailer, no load, reg temp outside.

I like to see mine in the around 160.

 

I run a Stage 2 Performabuilt 4L60E with a trans cooler from a 6.0L Powerstroke. I usually cruise on the highway around 120. Stop and go traffic, I'm usually around 150 - 160. I've almost never seen more than 170 on a really hot day.

 

Does atf not lubricate as well when cold?