Re: 91 Stingray / Mercruiser 3.0 135 HP Oil Changing question
Howdy, <br /><br />This is precisely what I did.<br /><br />That method is an alternative to inserting a (smaller)tube down into the pan via the dipstick tube.<br /><br />The advantage of connecting a larger tube (via the "water hose" type connection)is that everything goes faster because you are using a larger diameter tube. So even cold oil flows pretty good. If you use the inserted tube method, you can probably get the tube to go all the way to the very bottom or low spot in the pan and get "every last drop" of oil. That tube is of smaller diameter though to be able to fit inside of the dipstick tube.....so cold oil isn't going to flow very fast.<br /><br />The downside of using the water hose connection is that the tube might not get the last 1/2 inch or so of oil.....depending on how far down into the pan the dipstick tube goes. I would like to think that since OMC designed the oil to come out this way they made the tube go into the pan far enough to get most of the oil! (anyone here look into that?) I haven't had my pan off.<br /><br />I really don't think that's a real problem if you change your oil frequently. That little bit of "old" oil is not going to hurt anything unless it's severely contaminated with water, gasoline, etc. If that's the case you have much bigger problems that should be fixed.<br /><br />With most automotive/marine engines, if oil analysis is done, you would find that the oil can go MANY hours longer than most people run their oil.<br /><br />There's always a little residual oil in an engine either in the bottom of the pan or in the oil cooler and other places that it doesn't readily run back to the pan.<br /><br />I think when I did my 460 FORD engine last, I refilled it up using nearly the full fill amount within 1/4 qt or so. I sucked it out using a Moeller hand operated vacuum "sucker" that connected directly to the dipstick tube "water hose" connection.<br /><br />I think you can buy a 12v dc operated changer that will connect to the drain plug in any engine.<br /><br />It's basically a DC electric motor operated pump that sucks the oil out of the drain hole in the pan. They aren't cheap but they work pretty nice. <br /><br />I'll stick with the "oil sucker" I bought from Boaters world for about $60, it works great!<br /><br />Another way to do it might be to fabricate a copper or steel tube connection to the drain plug hole in the pan and bring it up to an area that you could get to. Then put a ball valve and a connection on it that you could connect your vacuum device or pump to and you would have a point where you could suck all the oil via the drain hole. The ideal way would be to do this when the pan is off so you place the drain tube in the lowest place in the pan and weld or braze it in place permanently.<br /><br />I'll probably do this on my next rebuild!<br /><br /><br />Regards, <br /><br /><br />Rick
