Last time i checked, i think it was 8 years because it's a long life coolant; just make sure to use genuine Honda Type 2 fluid. Do not use that all makes all models universal stuff because it doubt it's silicate free OR people just use tap water with all the minerals and stuff that screw up the tstat and water pump. I'm not a Honda Tech or anything just someone that slings parts all day long for a local parts store.