Does the rubber/hosing need to be replaced based on age or mileage? My car is nearing 200k miles, and I want to do as much preventative maintenance as possible, as it seems that I'll be keeping my IS F long term. Unless a hose is cracked, or leaking, do I need to concern about replacing it?

 

Not only hoses, but the plastics too - my car is 16 years old now and I just had the OEM radiator replaced at 75k as a preventive measure. - the plastic top was starting to rot and change colors.

 

I installed Figs radiator with the transmission cooling loop for this exact reason. Yes, my radiator got replaced under the fan screw recall, but my experience with all plastic tank radiators is they fail somewhere between 100k and 120k miles. So, when I replaced all the timing chains and tensioners, I swapped out the radiator too (and replaced the coolant pump, the alternator, and a few other bits that were definitely showing their age, but had not yet failed in service).

I considered replacing the rubber hoses, but they're still in excellent condition for the most part, so the ones that looked tired got replaced and the ones that still showed good life did not. They're sitting in a box waiting for the day I really need them at this point.