there are additives available that you put in right before an oil change and with running the motor at higher RPM for a few minutes are supposed to clean up old gunk. i wouldn't advise using them on a higher mileage engine due to the fact that that gunk is all that is sealing up the motor and it may burn oil after.
yea, i make sure the engine is warm before a tuneup..
i changed the oil, i first checked the dipstick and it was kinda clear but once i ran it around the block a few times, and checked it again it was black.. i figured id ask around here about it before getting frustrated.
i did however put some of that seafoam in the engine, carb and gas tank. Hopefully that will clean it out real nice.
then i'll change the oil again after about 1000 or so miles.