20JK10

I just want to verify which 4wd I should be using depending on the trail situation with an auto Jeep.

On an easy trails that are basically dirt paths with some minor dips, inclines, rocks, tree roots and what have you, would it be better to be in 4hi or 4lo? Speeds would not exceed 20mph.

I know when traversing rougher terrain, 4lo is better since you are going slower and want the additional power to the wheels to move over obstacles. Same thing when going up a steep hill with mud and rocks. In this case, would it be better to have the gear in 2nd or 1st?

When does the hot oil light usually come on, during 4hi or 4lo?

Can you leave the transfer case in 4hi/4lo when parked for a short period of time? Or would it better to put it back in to 2hi?

Greep

I've only gotten the HOT OIL warning on trails in 4hi. We were at 12,000 feet in Colorado. Switched to 4lo and no more problems.

Blakspire

Alright. 4HI is essentially when on-road conditions warrant 4-wheel drive, such as snow or ice. In 4HI you have no gear reduction, it is a 1:1 ratio, which means one turn in, one turn out. You will notice a substantial drop in power, since the engine now has to drive two axles. You can shift on the fly, as long as the front and rear axles are spinning at the same speed(no wheel slip). I would recommend keeping speeds 45MPH or slower. I'm sure the owners manual goes into that.

4LO is where you get your gear reduction, 2.72:1 for non-Rubicon, 4:1 for Rubicon. I drop it into four low any time I plan on wheeling the jeep, and most times I use second gear. If its something that is uber technical, I will use first gear. You cannot shift into 4LO on the fly. I wouldnt use 4LO at speeds anywhere above about 25.

You can leave the transfer case in any of the selected gearing options for as long as you require them (even when stopped). Do not engage 4wd any time you are on dry pavement. Always ensure tires have the ability to slip if necessary.

The HOTOIL light is a feature of the Automatic transmissions that will alert you to the possible overheating of the Automatic Transmission Fluid. When you will see it varies. In four high at low speeds (lots of torque converter slip) is where you are most likely to encounter it. To rectify the problem, stop the Jeep and place the transmission into park or neutral until the HOTOIL light shuts down.

Chamoru

I just got my 2012 Rubicon and took it out on a easy trail. I found that it was difficult to get it out of 4L. I am not experienced in 4 wheeling and had a couple of scares when shifting the transfer case. Sounded like I was breaking it. Could you share some of your knowledge of the basics. Still stressing if I did any damage to my Ruby.

Croce

Best way ive found to shift into/out of 4LO is to be travelling 2-5mph with the transmission in neutral.

Atch

Yep that's how you're suppose to do it

jeffncs

I know someone will come along to confirm / correct my response...

IIRC, the auto trans doesn't lock the fluid pump while in 2wd or 4-hi until 2nd or 3rd gear (forget). This means the trans pump isn't moving the full volume of oil through the trans, increasing fluid temps. Leaving the trans in 4-lo locks the fluid pump, increasing oil flow and reducing fluid temps.

Please correct me if I'm wrong...

This I know for fact - the addition of an external trans cooler is the best solution, hands-down. This is easily completed using basic hand tools and following installation instructions.

Jeff

Angst

If you are just driving down just a dirt road, just leave it in 2wd. I rarely use 4hi. I figure if I need 4wd I should be going slower. Plus with the rubi the sway bar disco and the lockers wont work in 4hi. It took me a while to learn to get into 4lo as well. You have to kind of coast it in neutral at 2-3 miles an hour. So it is a good idea to already have it dropped into that if you are attacking a big hill where you might need it.

FlameRedJK

If I recall correctly, Jeep recommends you go no faster than 5MPH in 4LO and 50MPH in 4HI
Only time I really use 4HI is going up steep hills or in the ice/snow...4HI is invaluable in the snow/ice!

keithvegas

Pretty sure it is max 25 in 4L