3000W Chinese Gensets Info.

I use synthetic (Amsoil) in all my engines, have had very good results except for 1 high mileage truck that I tried it in, had about 100k on it when I got it and the synthetic oil turned it into a sprinkler system, leaks every where!! The 2000 watt Genny unit I showed has approximately 500 hours on it now and shows no signs of any problems, still runs about 8 hours on a tank, no oil consumption, still starts on 1 pull, I change it after every weekend of use as all it takes is about a half a quart which I will probably do with the new Champion model as well. Oh here's a question, whats the thread size on the oil drain plug? It's not pipe thread, I want to extend it with a nipple so it will be easier and cleaner when doing oil changes.. Thanks

Slick