It pleases me that the folks out there advocating oil changes without changing the filter never really go away, but seldom convince many others to their way of thinking. I recognize that some of these folks are bouyed by supposed recommendations in some owners' manuals. Still others are making the case that filters are so good these days that they will simply go much farther than in the old days. There is a faction of people who will tie their habits to specific, long-lasting oils like HPL. There are some who are will advocate changing the filter at every 20 or 25,000 mile interval, but maybe changing the oil three, four or five times.
But I don't get it. You are already under the hood with wrenches. The price of the filter is really not that high. You may be arguing that you have cut the filter open and that it looks great. The fact is, you have no idea what you are not seeing in the filter, and a cut open filter will never tell you how long it operated in bypass.
Even if you are sure on the forgoing points, aesthetics alone would tell you that you are mixing old, dirty, depleted oil with new when keeping that old filter in place. I think most BITOGers see it this way.
But I don't get it. You are already under the hood with wrenches. The price of the filter is really not that high. You may be arguing that you have cut the filter open and that it looks great. The fact is, you have no idea what you are not seeing in the filter, and a cut open filter will never tell you how long it operated in bypass.
Even if you are sure on the forgoing points, aesthetics alone would tell you that you are mixing old, dirty, depleted oil with new when keeping that old filter in place. I think most BITOGers see it this way.