I just changed the oil on my Apex, drained the tank and the oil pan, didnt change the filter, it says to do it every second time or something like that in the manual. But anyways, it says to put in 3u.s. quarts, so I did and then after running it for a few minutes, then let it settle for a few minutes I checked the oil level without screwing in the dipstick, and it is just below the low line? How much is it suppose to take?