Most RV owners schedule generator maintenance based purely on hour meters, but generators care more about how hard they’ve worked than how long they’ve run. An hour spent powering just your lights and a small TV puts vastly different stress on the engine and electrical components than an hour running your air conditioner, microwave, and battery charger simultaneously.
Generators running at light loads — say, 25% capacity or less — actually develop different problems than those working harder. Light loads can cause carbon buildup because the engine never gets hot enough to burn off deposits completely. This is why many generator manuals recommend periodic exercise under heavy load, not just regular runtime. Running your generator monthly for an hour with minimal load actually does less good than running it quarterly while powering your AC unit.
The flip side is also true: generators consistently maxed out at 90-100% capacity wear differently than the hour meter suggests. High loads stress the voltage regulation system, cooling components, and engine internals more than normal use. If you frequently run multiple high-draw appliances, your oil changes and air filter replacements should happen ahead of the standard schedule, not just when the hour meter hits the magic number.
A better maintenance approach combines hours with load awareness. Keep a mental note of whether most of your generator time is light duty (maintaining batteries, running small appliances) or heavy duty (air conditioning, high-power tools, charging depleted battery banks). Heavy-use scenarios might need oil changes every 75 hours instead of 100, while very light use might safely extend to 125 hours. The key is understanding that identical hour readings can represent very different amounts of actual engine and electrical stress.