i concur w/segfault. use the 30 wt that came with the unit for break in. they usualy don't have the oil in the motors is correct! don't start! lol. then, i would switch to the 10-30 you have around. i don't think that using a good 10-30 would cause your machine to consume more oil than a hd 30 once it was broken in properly. you might, if concerned, try one of the "high milage" 10w30's as they are on the thicker side compared to regular 10-30's. also, i see you live in chicago, and you might find yourself using the washer on some colder mornings etc..the 10-30 should "sling" farther and faster. i wouldn't wait 50 hrs to change the oil either. that's when you are gonna get the most shavings and stuff out of the motor. change it after about the first 10 hrs of use. good luck!!!!