Clean oil, along with a clean air filter, is the most important thing in an engine no matter what type. I've seen too many engines totally destroyed well before their time, by the lack of attention in this area.
Honda generators, or any Honda engine, will easily last for 25 … 30 years if the oil is regularly changed. I’ve also seen this many times. I know of a mowing contractor whose main machines, Honda 2 speed self propelled mowers, are over 20 years old and still going strong.
Only use Honda Oil, of course, it is different to auto oil because of the temperature range of an air cooled engine compared to a water cooled engine. I've seen many air cooled engines that have been run on auto oil and it’s not a pretty sight. The oil seems to break down quickly and turn into a black syrup. I would strongly suggest … keep it simple and use Honda Oil.
To change the oil, run the engine for about 10 minutes to heat the oil. This will ensure most of the oil is drained as it is thinner to run out. With most generators simply tip the machine over toward the oil filler and drain into a container. Always dispose the old sump oil as per your local laws.
One thing to always keep in mind, when tipping any small engine over general rule of thumb is “air filter up”.
This means which ever way you tip it the air filter must be high as to not fill it with oil. Some machines it is not possible to do this, in this case always remove it before tipping.
If you change the oil quite often it would be wise to buy an oil suction tool. It’s like a big syringe with a tube on the end.
The tube feeds into the sump through the filler and you simple suck the oil out … no mess….find them on the accessories page…. Find the Honda Oil under Spare Parts.
Refill to the correct level with Honda Oil. With the machine straight and level, the oil starts to dribble out of the filler. Very clever … virtually impossible to overfill. Your done.