Got a question for you guys, I just replaced the oil in my Jeep myself for the first time instead of a dealership. I changed it from Conventional oil to a Synthetic Blend Valvoline Max life. Its been driven about 300 miles now and i checked the fluids in the car today after i cleaned the entire engine compartment (because it was filthy and oily) and i noticed the oil is already starting to turn brown. Is that normal for the oil to go from a bright amber color to a brown color in only 300 miles ? Im guessing it is and that the oil which is suppose to have extra cleaning agents is actually cleaning the engine.

I noticed the leak i had in the back of the inline 6 is not leaking anymore either.

Also about the radiator fluid. It was last changed probably 6 years ago. I looked inside today and the fluid in the tank looks brown. The fluid in the radiator cap tho is bright green. Should i drain the radiator and replace the fluid ? It doesnt overheat or anything im just wondering.

I've never used synthetic oil so I don't know.
You need to get rid of that old coolant and flush out your cooling system. Coolant should be changed every few years.