A. With OEM quality hoses, we would generally recommend that they be inspected annually and replaced every four or five years. Interestingly, hoses generally fail from the inside out due to electrolysis. Heat makes them harden and can lead to cracks. Oil can make them turn soft and spongy and even the ozone can lead to tiny parallel cracks in the hoses. Good preventive maintenance would suggest periodic replacement. we would suggest at least every five years.