The G2 does not need lube, thats the point of the delrin bushing.
I had one on my old gasgas, it was on it when I bought it, it lasted me a few years and is still going with no maitance or cleaning at all, I seen the bike last summer.
Unless you want a quicker or slower turning throttle theres no point in changing the stock throttle tube when running wrap around hand guards, its just not going to break.