Originally Posted By: Patman
Originally Posted By: irv
So, where do you draw the line? In my opinion, and I know this against what you guys are saying, if you are doing an oil change, isn't the purpose of the oil change to get as much of the dirty/used oil out as you can?
In most engines, even if you let the oil drain until every last drop comes out of the drain plug, and remove the filter too, you'll still have at least 5-10% of the old oil left behind in the heads and oil passages. So leaving behind an extra 2-3% on top of that isn't going to mean all that much. And if that old filter is actually doing a better job of filtering on the second OCI than it did on the first, it could possibly be better in the long run.
I know this has been beat to death, ad nauseam, but I have always wondered what people's limits were with how much used/spent oil they think is OK to leave in the engine?
Like I mentioned, getting as much of the used/spent oil out of an engine as I can just makes sense to me. Of course, there are limitations to that and if people were anal enough I am sure they would wait all night or 24 hrs for their vehicles to completely drain, or drain as much as possible, but while I'm doing one and set out about an hour of my time, maybe a bit more, I will do what I can during that time to ensure I've gotten out as much as possible.
Yesterday, I did an OC on my Yamaha Vector 4 stroke snowmobile. It is a dry sump setup with an oil tank on the side. If I just let it sit level while doing it, I only get so much used oil out of it but if I raise the front up with a floor jack, it's amazing how much more dirty/used oil comes out of the block and tank. I can only raise it so high, which is good enough for me, but it's reassuring knowing I got as much used/dirty oil out as possible.
Doing this allows me to add 3.1 litres of new oil but if I didn't do a filter change and raise it, it would only accept 2.6 litres. I know a half litre is not much but when the total capacity is 3.8 in a new engine, that 1/2 a litre is significant in my opinion, especially when one considers the RPM's these engines spin at.
(No floor jack yet in this pic, just the front dollies to raise it slightly to give me a bit more room under there)