I bought my 2015 Infiniti Q50 second hand about a year ago, and last week I finally looked at the service papers properly. I found oil changes, brake pads and a new battery, but nothing at all about the cooling system. No flush, no hoses, nothing. The car has about one hundred and ten thousand kilometers, and it lives in the Abu Dhabi sun, so now I cannot stop thinking about it. The temperature needle is normal, there is no puddle under the car, and nothing looks wrong, which is exactly why I am unsure what to do. My brother says leave it alone, because a flush on an old system can loosen rust and old deposits and start leaks that were not there before. My colleague says the opposite, that old coolant turns acidic and eats the radiator from the inside, so waiting is the real risk. My wife says I should simply do what the service book says and stop worrying. One evening I read about premium Infiniti radiator repair in Musaffah Shabiya, and it gave me a rough idea of the work, but it did not explain whether a healthy radiator needs a flush at all, so I would like to hear from real owners. First, how often do you change the coolant in this heat, every two years, every four years, or only when something goes wrong? The book gives a long interval, but I wonder if that is meant for cooler countries. Second, is there a simple way to check the condition of the coolant myself? Someone told me that rusty brown color or oily bits floating in the tank are bad signs, while clean green or pink is fine. Is that right, and is it safe to look when the engine is cold? Third, what is the difference between a simple drain and refill and a full flush with a machine? I heard the machine type costs more, and I do not know if it is better or just more money. Another thing I wonder about is the type of coolant. Some people say you must use the exact original type and never mix colors, because it can turn into sludge. Is that true, and how do I know what my car uses? Also, should the garage test the radiator cap and the hoses at the same time, since they are old too? And how long does the whole job take, because I need the car every day for work? If you did a flush on an older Infiniti, did it cause any problems afterwards, what did you pay, and would you do it again?