Hi
If your engine is after a certain year (not sure what that is though...guessing late 90's or early 2000's. More learned guys will surely comment??) it may have the hose fitted already.
I have always used the out the dipstick method on all variants on the gm engines...mainly because I didn't have a choice. Up until recently I didn't have an engine that had the hose.
Now that I have the hose and after 2 years of ownership, I can tell you the following;
First year I took the oil out through the dipstick (not using the screw on pump on hose thread on dipstick, but with a pela extractor with thin hose that you can physically feel reaching the bottom of sump) and took about 4l out. I then put 4l back in and all was well.
This year, whilst having time on my hands with the poor weather, I decided to have a go at the hose out the drain plug. I initially had no idea I took out, because it was draining into a basin under the boat and it took about an hour. I was convinced I was doing the right thing by the engine and also that I had surely taken out more than before (even ran the engine beforehand to ensure all the particles and impurities were suspended). After all this...and the hassle of pushing it out the drain hole in first place...I refilled the oil to the correct level and replaced filter. I was surprised to see that she took exactly 4l as before !
Not sure is I'll be doing the latter again. The dipstick removal method (as long as you are getting to the bottom of the sump) seems to be near as dammit as effective.
