Perpetual Oil Changes?
Road Master
Joined: Aug 2012
Posts: 944
Likes: 2
From: Ct
found this today, check it out, I this answers the OP's original question about getting all the oil out.
https://www.hdforums.com/forum/touri...g-2007-up.html
Pretty neat.
Lump
https://www.hdforums.com/forum/touri...g-2007-up.html
Pretty neat.
Lump
Road Master
Joined: Aug 2012
Posts: 875
Likes: 2
From: Where I lay my head is home.
Wow... I'm a pioneer I guess. I did this with just about every car I had until my mid 20's. Let a quart leak onto the driveway over a few weeks or so... put a fresh quart in the filler tube. Genius!
Elite HDF Member
Joined: Nov 2010
Posts: 3,846
Likes: 173
From: Simi Valley, CA
I don't do, nor do I plan to do, the "perpetual" oil change thing but if you really think about it from a engineering perspective I see no real disadvantage with the method.
Here's my rationale.
The oil in your bike accumulates contaminants and depletes the oil's additive in a fairly linear manner over time. Assume your bike holds four quarts of oil. If you change those four quarts at specified intervals, let's assume 4,000 miles, and assuming you get all of the old oil out, you will then have what I'll call peak oil condition. At 2,000 miles you will have what I'll call intermediate oil condition. And at 4,000 miles you will have what I'll call the worst oil condition. Over those 4,000 miles your oil will be at it's best early on and at it's worst as you approach the 4,000 mile change interval.
Now consider the perpetual method. If you replaced one quart of oil every 1,000 miles, you would have cycled through four quarts of oil over the same 4,000 mile change interval. The only difference is your oil will never be at it's peak condition, like when you do a complete change, but it will never be at its worst condition either, like when you're approaching the 4,000 mile change interval.
What you will have is an oil close to its intermediate condition "perpetually" over 4,000 miles rather than an oil transitioning from it's best to it's worst over the same 4,000 mile period of a conventional oil change.
Personally, I think your engine's protection would average out and be pretty close to equal over the long haul with either the conventional oil change or the perpetual oil change.
Food for thought, hey?
Here's my rationale.
The oil in your bike accumulates contaminants and depletes the oil's additive in a fairly linear manner over time. Assume your bike holds four quarts of oil. If you change those four quarts at specified intervals, let's assume 4,000 miles, and assuming you get all of the old oil out, you will then have what I'll call peak oil condition. At 2,000 miles you will have what I'll call intermediate oil condition. And at 4,000 miles you will have what I'll call the worst oil condition. Over those 4,000 miles your oil will be at it's best early on and at it's worst as you approach the 4,000 mile change interval.
Now consider the perpetual method. If you replaced one quart of oil every 1,000 miles, you would have cycled through four quarts of oil over the same 4,000 mile change interval. The only difference is your oil will never be at it's peak condition, like when you do a complete change, but it will never be at its worst condition either, like when you're approaching the 4,000 mile change interval.
What you will have is an oil close to its intermediate condition "perpetually" over 4,000 miles rather than an oil transitioning from it's best to it's worst over the same 4,000 mile period of a conventional oil change.
Personally, I think your engine's protection would average out and be pretty close to equal over the long haul with either the conventional oil change or the perpetual oil change.
Food for thought, hey?
Road Warrior
Joined: Sep 2010
Posts: 1,260
Likes: 44
From: Back woods of Maine
The mill where I used to work does perpetual oil changes. This involves heating the oil to boil off contaminates and then centrifuging it to remove solids. It is a practical method only because we are treating many thousands of gallons at a time. It doesn't make much sense to me on a small engine. The only way that you could do it properly would be to have a sample of the oil tested to make sure that your lubricating properties were intact. I think that you should just do your regular oil changes.
I think I will stick with the regular intervals. When you mentioned perpetual oil changes I thought you might have been talking about a bad oil leak. I read a post somewhere about a guy who just kept adding oil but never did any changes. 
Seasoned HDF Member
Joined: Jan 2011
Posts: 157,527
Likes: 57,084
From: Michigan 15 Minutes East Of Hell
Excellent analogy "t. sawyer" ... and "mkguitar" has hit the nail right on the head regarding acids that form in the oil ... they are corrosive and will lead to premature wear ... Change all the oil and filter each time ... After all you got a $20,000.00 scooter .... what's another $40.00 for fresh oil ... just my .02 cents worth Brother.
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