Nice and long, it was a cloudy day here so it was not grate to see the smoke. i had to pinch the bission injector so i can slow down the flow to 2oz per minute i am going to lower it a bit more to see the difference i am still getting some oil on the botem of the plane but not as much as my first run with a stock injector .it took me a while to figure out the mix with the throttle on my radio as i lower it so dose the flow of oil , i am using a mix of baby oil , diesel , and auto tyranny fluid for now. as soon there is a container coming to Croatia from the states i am picking up a gal or two. with my mix it did not last to long it was a slight breeze and it dissipated pretty quick. also i have not see or heard of a pre heater what is it and how dose it work i understand it heats the oil before it goes in to the muffler . what kind of set up. and how dose it work