External breather emissions
Tourer
Joined: Jun 2014
Posts: 311
Likes: 3
From: OHIO
Running the oil level at the half-way mark is not "under-servicing", or incorrect. On a dry sump setup, the oil system will function exactly the same at different reservoir levels, as long as the oil pickup stays submerged. The only difference is that when the oil level is high in the reservoir on our bikes, more will be splashed into the reservoir vent tube, and be blown out the breathers.
On an air-cooled engine which relies on splash lubrication (rather than being pressure-fed), you'd be right that oil level is much more critical. You'd also be right that if we had a completely separate oil tank (like on a softail), when the oil level is higher in the tank, there might be slightly more heat transfer from the oil, to the walls of the tank, and then to the air. But our Dyna oil tanks are essentially one-piece with the engine/transmission assembly, so added cooling from running a higher oil level would be practically non-existent.
On an air-cooled engine which relies on splash lubrication (rather than being pressure-fed), you'd be right that oil level is much more critical. You'd also be right that if we had a completely separate oil tank (like on a softail), when the oil level is higher in the tank, there might be slightly more heat transfer from the oil, to the walls of the tank, and then to the air. But our Dyna oil tanks are essentially one-piece with the engine/transmission assembly, so added cooling from running a higher oil level would be practically non-existent.
No joke. I have been filling mine to a little over 1/2 and under 3/4 when hot. I'm glad you posted this because I was concerned.
Respect.
Outstanding HDF Member
Joined: Dec 2012
Posts: 2,557
Likes: 235
From: Texas
Running the oil level at the half-way mark is not "under-servicing", or incorrect. On a dry sump setup, the oil system will function exactly the same at different reservoir levels, as long as the oil pickup stays submerged. The only difference is that when the oil level is high in the reservoir on our bikes, more will be splashed into the reservoir vent tube, and be blown out the breathers.
On an air-cooled engine which relies on splash lubrication (rather than being pressure-fed), you'd be right that oil level is much more critical. You'd also be right that if we had a completely separate oil tank (like on a softail), when the oil level is higher in the tank, there might be slightly more heat transfer from the oil, to the walls of the tank, and then to the air. But our Dyna oil tanks are essentially one-piece with the engine/transmission assembly, so added cooling from running a higher oil level would be practically non-existent.
On an air-cooled engine which relies on splash lubrication (rather than being pressure-fed), you'd be right that oil level is much more critical. You'd also be right that if we had a completely separate oil tank (like on a softail), when the oil level is higher in the tank, there might be slightly more heat transfer from the oil, to the walls of the tank, and then to the air. But our Dyna oil tanks are essentially one-piece with the engine/transmission assembly, so added cooling from running a higher oil level would be practically non-existent.
I have seen many VW and aircraft engines (same oil pump setup) trashed because of intentionally or unintentionally under servicing the oil. The engine overheats for some reason or another, the oil breaks down and loses viscosity, and something goes pop.
Last edited by skinman13; Jun 5, 2015 at 02:57 PM.
Outstanding HDF Member
Joined: Dec 2012
Posts: 2,557
Likes: 235
From: Texas
I plan on replacing the filter when I see evidence of oil filling it up...easily visible by looking at the filter element. I have around 300 miles on the setup with no sign of oil on the filter so far.
Outstanding HDF Member
Joined: Aug 2012
Posts: 3,217
Likes: 90
From: Detroit
If you say so...it's your choice and your engine. I am not saying that you are wrong, but I think it may be a little irresponsible to advise or suggest that anyone else to do this considering that it does not comply with MoCo's recommendations. Just say'n.
I have seen many VW and aircraft engines (same oil pump setup) trashed because of intentionally or unintentionally under servicing the oil. The engine overheats for some reason or another, the oil breaks down and loses viscosity, and something goes pop.
I have seen many VW and aircraft engines (same oil pump setup) trashed because of intentionally or unintentionally under servicing the oil. The engine overheats for some reason or another, the oil breaks down and loses viscosity, and something goes pop.
2. VW isn't a dry sump system.
3. Overheating any engine can be a problem. Often, the failure isn't from lubrication breakdown, but because the piston expands more than the bore, leaving insufficient clearance. That heats the engine and oil even more, and you're on a downward spiral.
Road Master
Joined: Dec 2012
Posts: 848
Likes: 30
From: CO
I beg to disagree. Regardless of what you think about dry-sump systems...ALL air cooled engines need the correct oil level to help keep them cool as well as lubrication. Intentionally under servicing your oil level, even by a few ounces, is just inviting a serious engine failure someday...just say'n
I remember you telling people that keeping a battery tender on our AGM batteries every day would ruin them. You seem to be quite the alarmist.
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Extreme HDF Member
Joined: Feb 2015
Posts: 10,907
Likes: 8,758
From: Galt's Gulch - MI
Running the oil level at the half-way mark is not "under-servicing", or incorrect. On a dry sump setup, the oil system will function exactly the same at different reservoir levels, as long as the oil pickup stays submerged. The only difference is that when the oil level is high in the reservoir on our bikes, more will be splashed into the reservoir vent tube, and be blown out the breathers.
On an air-cooled engine which relies on splash lubrication (rather than being pressure-fed), you'd be right that oil level is much more critical. You'd also be right that if we had a completely separate oil tank (like on a softail), when the oil level is higher in the tank, there might be slightly more heat transfer from the oil, to the walls of the tank, and then to the air. But our Dyna oil tanks are essentially one-piece with the engine/transmission assembly, so added cooling from running a higher oil level would be practically non-existent.
On an air-cooled engine which relies on splash lubrication (rather than being pressure-fed), you'd be right that oil level is much more critical. You'd also be right that if we had a completely separate oil tank (like on a softail), when the oil level is higher in the tank, there might be slightly more heat transfer from the oil, to the walls of the tank, and then to the air. But our Dyna oil tanks are essentially one-piece with the engine/transmission assembly, so added cooling from running a higher oil level would be practically non-existent.
The oil level is not low unless it's at the lower mark on the stick, the word 'full' on the stick is nothing but a source of constant confusion. Per the manual if you're at the lower mark you'd only add enough oil to bring it back to the middle of the stick on a cold bike and that's only a few ounces at most to do so. Running at the top of the stick just leads to carryover into the breathers.
Seasoned HDF Member
Joined: Mar 2010
Posts: 38,586
Likes: 6,435
From: Honah Lee
Harley's are only a dry sump in the fact that the oil is not stored in the crankcase. A Softail has it in the bag above the transmission. Dynas and the large cruiser in the tank below the transmission. All Harleys run with some oil in the crankcase that is being constantly dumped in and pulled off by the two stacked suction and pressure oil pumps The suction return is larger than the pressure one but the pickup for it leaves oil in sump.
This oil left is spun by the two large crank rotors (sort of like flywheels) . This is the main lubrication for the inner cam needle bearings. In the older engines before the cooling piston jets that are in are twin camshaft engines for cooling, the spinoff was what cooled the inside of the pistons. Note that the jets do not operate at idle oil pressure and in hot parts of the country, modifying the oil pressure for pressure above 12lbs at idle will cook the oil.
You can overfill a Harley but it is truly hard to get too much oil in the crankcase. On a Softail, you really cannot and it will come out the tank plug if you do. However, they will sometime drain down into engine if left sitting for a long time. Know mine does but it does not go far even after 3-4 months. On a big cruiser or Dyna with a screw in oil cap, guess you can but it is a small amount simple since there is only so much room above full. Unlike a car, the oil should be checked right after you turn it off (especially on a Softail) and unless it's hot, should be at the middle between the low and full line. If it's truly hot, it can be at the full mark. That does not cause problem.
This oil left is spun by the two large crank rotors (sort of like flywheels) . This is the main lubrication for the inner cam needle bearings. In the older engines before the cooling piston jets that are in are twin camshaft engines for cooling, the spinoff was what cooled the inside of the pistons. Note that the jets do not operate at idle oil pressure and in hot parts of the country, modifying the oil pressure for pressure above 12lbs at idle will cook the oil.
You can overfill a Harley but it is truly hard to get too much oil in the crankcase. On a Softail, you really cannot and it will come out the tank plug if you do. However, they will sometime drain down into engine if left sitting for a long time. Know mine does but it does not go far even after 3-4 months. On a big cruiser or Dyna with a screw in oil cap, guess you can but it is a small amount simple since there is only so much room above full. Unlike a car, the oil should be checked right after you turn it off (especially on a Softail) and unless it's hot, should be at the middle between the low and full line. If it's truly hot, it can be at the full mark. That does not cause problem.
Last edited by Jackie Paper; Jul 5, 2015 at 11:42 AM.