Here, check this out for some enlightenment.

Radiator Flush - JeepForum.com

Just wanted to throw this out since you're learning: If you're just topping up on the coolant, the engine doesn't need to be running. If you're refilling the coolant after draining it (like after replacing the water pump), then you would want to fill through the expansion tank and then start the engine to circulate the coolant to remove any trapped air. Keep topping up until it stays at the max line. Also check the level again after driving it the first time. (Be sure to replace the expansion tank cap before driving)

And NEVER remove the expansion tank cap if the engine is hot. Always wait for the engine to cool down.

ummm NO! Please lets not give bad advice guys.... if you don't know don't post. you must have the engine warmed up to normal operating temp BEFORE adding any coolant. This is the only way you will know if your coolant is low. please read your manual. The coolant expands as it is heated and if you just add coolant when its cold you will overfill it. this will do two things. 1) make a huge mess on your driveway and around town as you splash coolant everywhere. 2) you could damage your cooling system by having too much coolant creating excessive pressure that may cause excessive wear on parts. (water pump, hoses, radiator, cap seals etc.) also only use MOPAR HOAT do NOT mix different coolant types, you will regret it.

Engine Coolant Level
The coolant bottle provides a quick visual method for
determining that the coolant level is adequate. With the
engine idling, and warm to normal operating temperature,
the level of the antifreeze/coolant in the bottle
should be between the ranges indicated on the bottle.The radiator normally remains completely full, so there is
not need to remove the radiator cap unless checking for
antifreeze/coolant freeze point or replacing antifreeze/
coolant. Advise your service attendant of this. As long as
the engine operating temperature is satisfactory, the
coolant bottle need only be checked once a month.
When additional antifreeze/coolant is needed to maintain
the proper level, it should be added to the coolant
bottle. Do not overfill.
Adding Engine Coolant
Your vehicle has been built with an improved antifreeze/
coolant that allows extended maintenance intervals. This
antifreeze/coolant can be used up to 5 Years or 100,000
miles (160 000 km) before replacement. To prevent reducing
this extended maintenance period, it is important that
you use the same antifreeze/coolant throughout the life
of your vehicle. Please review these recommendations for
using Hybrid Organic Additive Technology (HOAT)
antifreeze/coolant. When adding antifreeze/coolant:
² The manufacturer recommends using Mopart
Antifreeze/Coolant 5 Year/100,000 Mile Formula
HOAT (Hybrid Organic Additive Technology).
² Mix a minimum solution of 50% HOAT engine coolant
and distilled water. Use higher concentrations (not to
exceed 70%) if temperatures below -34°F (-37°C) are
anticipated.
² Use only high purity water such as distilled or deionized
water when mixing the water/engine coolant
solution. The use of lower quality water will reduce
the amount of corrosion protection in the engine
cooling system.Please note that it is the owner’s responsibility to maintain
the proper level of protection against freezing according
to the temperatures occurring in the area where
the vehicle is operated.
NOTE: Mixing antifreeze/coolant types will decrease
the life of the antifreeze/coolant and will require more
frequent antifreeze/coolant changes.


CAUTION:

Mixing of antifreeze/coolants other than the specified
HOAT antifreeze/coolants, may result in engine
damage and may decrease corrosion protection.
If a non-HOAT antifreeze/coolant is
introduced into the cooling system in an emergency,
it should be replaced with the specified
antifreeze/coolant as soon as possible.² Do not use plain water alone or alcohol-base
antifreeze/coolant products. Do not use additional
rust inhibitors or antirust products, as they may
not be compatible with the antifreeze/coolant and
may plug the radiator.
² This vehicle has not been designed for use with
Propylene Glycol based antifreeze/coolants. Use
of Propylene Glycol base antifreeze/coolants is not
recommended.
MAINTAINING YOUR VEHICLE 379
7

Lol. Good one!

I guess I should have been more specific. You do need the engine up to normal operating temperature to verify proper coolant level, but you want to do this by starting with the the engine cold and removing the expansion tank cap, then running the engine until it gets up to temp. As I said before, NEVER remove the cap with the engine already hot as the system is under pressure at that point and you can end up with hot coolant all over you. With the cap off, the pressure does not build in the system as the engine heats up.

That being said, this is really the proper method when topping off the system as well as refilling after draining, so my previous advice was a bit flawed.

I removed the cap on a hot engine when I was a teenager and still learning. You wouldn't believe how high that stuff shoots out of the radiator cap!!

By chance my head was not over the radiator or I'd have been badly burned. So lucky.

Ya I'd say you got really lucky, everyone learns from mistakes right

friend of mine did that on his first car as a teenager. Cap hit him just above the eye; he said he felt like he had been hit by a pitch.

Dangerous stuff.

I dont know about you guys but my 07 has the orange dexacool coolant in the system. I had to add a half of jug of premixed orange fluid the other day for the first time.

Do you know it's Dex-cool or are you just going by color?

For what it's worth the "yellow" G-05 looks reddish-orange in my JK, but it is now 5yrs old and getting flushed next week. (along with my 5 yr old brake fluid...)

If it's the OEM fill it isn't Dex-cool (OAT) it is the G-05 HOAT. Chrysler switched to HOAT in 2001 (and just changed to a new, unique OAT for 2013).

And if it is the OEM fill, it "expired" on you a year or two ago.