buy this kit:
Step 1: drain the radiator into a 5-gallon bucket, cap it, and install the flush kit as directed by the instructions, then fill the system up with the garden hose. flush the system by leaving the radiator cap off as directed by the instructions.
Step 2: after flush is complete, turn the hose off and remove it. drain the system again and cap the flush T. refill the whole system (radiator & bottle) with distilled
water and go for a drive to pump the distilled water around & get the system hot. or you can leave the radiator cap off till the engine gets hot enough to push water out.
Step 3: drain the distilled water out from the radiator. mix up a 50/50 mix of one gallon of Zerex GO5 (or your choice HOAT antifreeze) with one gallon of distilled water in a clean 5 gallon bucket. Use an anti-freeze tester to verify concentration. Dump that into the radiator. Remember, there will be roughly half a gallon of distilled water remaining in the engine block, so factor that into your mixture by testing the anti-freeze concentration repeatedly as you fill it. You can dump straight anti-freeze into the radiator at the end to cut the mixture to the proper concentration.
Step 4: as you fill, keep squeezing the top radiator hose. it will burp air out as you do so. once you can't burn any more air out with the hose, dump the remaining 50/50 mix into the overflow bottle till it reaches the "hot" mark. Now, start the jeep up and let it heat up enough to open the thermostat...going for a drive will make this happen quicker.
Step 5: top off the overflow bottle as necessary. remember, the thermostat should have a small hole in it to bleed air off, and heating the engine up pushes all the air to the thermostat and allows it to be pushed into the radiator, where it sits at the top of the radiator and is pushed into the overflow bottle, where its vented off.
Thats my modified version of how the FSM directs you to do it, and I've flushed three times like this and it works great for me.