Originally Posted By: BlueOvalFitter
Originally Posted By: y_p_w
Originally Posted By: tig1
For the extra cost(maybe 2 cents or less per day at 10K OCIs)I won't put 4 qts of new oil mixed with 1/4 to 1/2 of old oil. Honda should know better than this silly argument.
What's wrong with old oil in there, other than an antiquated belief that you need to get out as much used oil as possible? I'd hope that by the time the oil is changed, the used oil is still protecting the engine and the additives haven't been totally depleted. An oil change is primarily replenishing the oil's additives and putting in new base oil. You're renewing it and not completely replacing it. You've got a filter to keep out stuff that will damage the engine if allowed to recirculate. I've thought that a good idea might even be to have an oiling system where only half the oil is removed on each oil change. I've heard reports that engine wear actually goes up after an oil change for a few hundred miles - primarily because the antiwear additives take time to heat activate. The only difficulty of that is when changing oil weights or worries about incompatibilities if the new oil is vastly different than the old oil. Automatic transmissions universally deal with old fluid.
There's typically more oil than that left in a car even after a full drain. So there's 1/4 quart of oil in a filter that stays in there. How big a deal is that when there's already a half quart or more that remains in the oil galleys or sitting on top of the valve train? Recently I've shined a light in the filler cap of my wife's Civic. You can see several of the valves and the valve lash adjustment. There's lots and lots of oil still there, including in some areas where it will remain there indefinitely because it's physically trapped and not removed until oil from the sump is splashed there and displaces it.
This was a fun discussion on this issue of oil remaining in the engine after most of the oil drained. The consensus was that a brand new engine might need anywhere from a half quart to 1.5 quarts more oil than required for a "full" oil change with filter. One guy looked at his Civic's owner's manual, which specified an oil capacity of 4.7 quarts but a full oil change (with filter) at 3.9 quarts. So what's the practical difference between 0.8 quarts of the existing oil remaining and 1.0 quarts?
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1165846&page=all
With my wife's Civic, the total capacity is 4.4 quarts but with a full oil change capacity of 3.4 quarts and an oil only change of 3.2 quarts. So about 23% of the old oil remains there after a regular oil change with filter, and 28% without a filter change.
honda.com/assets/OWNERLINK/Model/own_man/2002CivicSd.pdf
I think there's an old expression to describe arguments of little significance. How many angels can dance on the head of a pin? We're debating if a quarter quart of oil left in an oil filter is creating more wear, when there's already a full quart or more of oil left behind. They've already thought of that oil and figure it's not reducing longevity. In fact I think it's probably helpful for longevity because the remaining oil already has activated antiwear additives and because it helps protect engine parts before oil pressure is built up. I doubt you'd actually want to start with every last bit of oil teleported out of there and new oil poured in the engine. The people designing these engines are fully cognizant that there will be old oil left in there regardless of whether or not the filter is removed.
"One Filter, One OCI!"
That's what I usually do. However, I did change oil only a few times during breakin and once on my wife's Civic because I couldn't reach the filter without ramps.
However, what I was getting at was that worrying about 1/4 quart of oil remaining in an unchanged filter ignores that there's another quart of old oil that's not coming out without removing the valve cover and sponging it off or sucking it out. Getting that additional 1/4 quart out is essentially meaningless in terms of protecting the engine.
Originally Posted By: y_p_w
Originally Posted By: tig1
For the extra cost(maybe 2 cents or less per day at 10K OCIs)I won't put 4 qts of new oil mixed with 1/4 to 1/2 of old oil. Honda should know better than this silly argument.
What's wrong with old oil in there, other than an antiquated belief that you need to get out as much used oil as possible? I'd hope that by the time the oil is changed, the used oil is still protecting the engine and the additives haven't been totally depleted. An oil change is primarily replenishing the oil's additives and putting in new base oil. You're renewing it and not completely replacing it. You've got a filter to keep out stuff that will damage the engine if allowed to recirculate. I've thought that a good idea might even be to have an oiling system where only half the oil is removed on each oil change. I've heard reports that engine wear actually goes up after an oil change for a few hundred miles - primarily because the antiwear additives take time to heat activate. The only difficulty of that is when changing oil weights or worries about incompatibilities if the new oil is vastly different than the old oil. Automatic transmissions universally deal with old fluid.
There's typically more oil than that left in a car even after a full drain. So there's 1/4 quart of oil in a filter that stays in there. How big a deal is that when there's already a half quart or more that remains in the oil galleys or sitting on top of the valve train? Recently I've shined a light in the filler cap of my wife's Civic. You can see several of the valves and the valve lash adjustment. There's lots and lots of oil still there, including in some areas where it will remain there indefinitely because it's physically trapped and not removed until oil from the sump is splashed there and displaces it.
This was a fun discussion on this issue of oil remaining in the engine after most of the oil drained. The consensus was that a brand new engine might need anywhere from a half quart to 1.5 quarts more oil than required for a "full" oil change with filter. One guy looked at his Civic's owner's manual, which specified an oil capacity of 4.7 quarts but a full oil change (with filter) at 3.9 quarts. So what's the practical difference between 0.8 quarts of the existing oil remaining and 1.0 quarts?
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1165846&page=all
With my wife's Civic, the total capacity is 4.4 quarts but with a full oil change capacity of 3.4 quarts and an oil only change of 3.2 quarts. So about 23% of the old oil remains there after a regular oil change with filter, and 28% without a filter change.
honda.com/assets/OWNERLINK/Model/own_man/2002CivicSd.pdf
I think there's an old expression to describe arguments of little significance. How many angels can dance on the head of a pin? We're debating if a quarter quart of oil left in an oil filter is creating more wear, when there's already a full quart or more of oil left behind. They've already thought of that oil and figure it's not reducing longevity. In fact I think it's probably helpful for longevity because the remaining oil already has activated antiwear additives and because it helps protect engine parts before oil pressure is built up. I doubt you'd actually want to start with every last bit of oil teleported out of there and new oil poured in the engine. The people designing these engines are fully cognizant that there will be old oil left in there regardless of whether or not the filter is removed.
"One Filter, One OCI!"
That's what I usually do. However, I did change oil only a few times during breakin and once on my wife's Civic because I couldn't reach the filter without ramps.
However, what I was getting at was that worrying about 1/4 quart of oil remaining in an unchanged filter ignores that there's another quart of old oil that's not coming out without removing the valve cover and sponging it off or sucking it out. Getting that additional 1/4 quart out is essentially meaningless in terms of protecting the engine.
