I guess I'll walk into this mine field. Let me ask are you having cooling problems - yes or no? If yes then you need to look at other things first, If no then just do routine maintenance.
I see on your profile you have a 91 XJ. Have you done normal maintenance stuff? When was the last time you changed:
* Radiator
* Upper and lower radiator hoses
* heater hoses
* Thermostat
* Radiator cap
* Fan clutch for mechanical Fan
* Fan belt
* coolant
My guess is most of it could still be stock. Before we head down the modified fan route lets make sure the system is working good.
I personally change my hoses and fan belts every 4 years regardless of mileage. I did them in 2000 and just did them again 2 weeks ago. This time I picked up the radiator hoses at the dealer, figure on $20 each but they are very nice! The lower has the spring inside to prevent collapse. Also both upper and lower came with the anti-chafe installed, I would recommend everyone use the dealer hoses and they were within a buck of what autozone wanted for their best hoses, the Goodyear ones.
In high school my dad maintained our cars "on condition" instead of doing preventive maintenance. In college we were at a relatives house, the 69 camero has a bad upper hose, he cut off the last inch and told me to drive it. The next town with a parts store was 35 miles away. I did not want to break down so I changed the hose at the relatives house once I found one in the town of 1700 people. I am big on making sure the cooling system is only down when I want it to me... not having it influence my schedule.
If you are running hot change out the mechanical fan clutch, there is NO good way to test them. I replaced the factory one in 2000 and replaced it again 2 weeks ago. The consensus on here is the clutch may last 5 years so while I had the radiator out it was no more effort. I also installed a new Mopar 195F thermostat.
My guess is you still have the factory radiator. I installed a GDI 4 years ago and been adding a pint to quart every 1000-3000 miles. I installed a new Modine and it holding fine. I had a leak in the GDI where the tubes attach to the end plates but was not to leave anything on the ground. I could see the white residue when I had the mechanical fan shroud pushed out of the way and was real easy to see when I pulled it out of the XJ.
With the radiator out this would be an ideal time to replace ANYTHING on the front of the engine - water pump, harmonic balancer, etc. I did my water pump 2 years ago since it had 135,000 on it and the balanacer was done at the garage 4 years ago when it began to walk toward the radiator and caused the fan belt to break.
If you change the belt spin all the accessories to see if they turn smoothly. I highly recommend you change the idle pulley by the AC compressor. Also install the belt using the Kriket II belt tension gauge. I posted the NAPA P/N stuff in the past week. Made installing a new belt easy work, no guessing on the tension!
When you refill with coolant use distilled water instead of tap and pull the temp sensor out of the head, if you have one, when you are filling to get the air out of the block.
Like I said if you are running just fine then let the sleeping dog lay but if you are running warm time to do cooling system maintenance BEFORE you start a science experiment with the electric fans.