Cars have a mileage and a time interval for changing timing belts on our older cars. 90k or 10 years, 80k or 7 years, etc. With, what I am understanding, this new fangled rubber compounding has there been any change in these intervals? "Originally Posted by Boomer Looks like it is made from hydrogenated nitrile butadiene rubber....very oxygen and oil resistant material." My understanding is more timing belts break due to time versus mileage. If that is the case, how long do you go before changing your timing belts? Time wise.