Going up Palomar Mountain Trail today (San Diego) and my hot oil notice came on. Never seen that before. Pulled over and shortly after it went away and didn't come back on the 8 mile trip up the mountain. Have to do some research but any experience with this?

 

Transmission fluid overheated. Do you have an additional transmission cooler installed?

 

No sure dont. Never had any need for one. What makes an-additional one required? Never had the light come on until today

 

The 42RLE transmission cooler is too small and not in the direct flow of air through the grill. It's at the bottom of the A/C condenser, behind the bumper.

It is a common recommendation to install an additional cooler in all 42RLE equipped JKs; pre-2012 JKs, that is.

The hot oil light was an update to the transmission software a few years ago for some of the early JKs.

The main source of heat in the automatic transmission is an unlocked torque converter.
The fluid overheats when the torque converter stays unlocked for an extended time as when going up a long hill at a speed too slow to allow the transmission to get into 3rd gear, or under too much load to allow the torque converter to lock if it makes it to 3rd.
If you put the lever in 2 or 1, it will never lock.

 

Wow. Thanks for the detailed info. Sounds like exactly what happened. I typically just do fire roads etc but followed some guys up the mountain today. Doubt I would have a need for it too often but Ill see how it goes. Thanks again for the info!

 

While this tread is current does anyone have any recommendations for a cooler? What is the benefit of a cooler(without an electric fan)while cruising in 4lo especially over hot summer days?

I'd like to get a cooler with a fan but not sure which route to go or if I even should.

 

What year is your JK?

 

2010 2 door

 

B&M is a popular brand.
Electric fan is not required. The cooler will have air through it from forward motion, or when the engine's electric fan comes on. You can force the engine's electric fan to come on by turning on the A/C.

There are lots of threads dealing with the different brands and their installation instructions.

 

Yeah I just can't see how the cooler would help going 1-2 mph for 8 hours. The engines fan could put air through the cooler? B&M looks good. So does the mopar cooler.