The aerated oil in the tank is pretty normal for a Harley. They are considered dry sump but actually run 1 1/2" or so of oil on the bottom being replaced all the time since the oil pump return is about that high off the bottom. The oil is thrown in at the top of the tank and being drawn off the bottom. Unlike an auto transmission, it does not hurt anything. Just out of curiosity, how thick is that oil. For 50 miles, it has a strange color and looks quite thick by the fact that it's rounded on the stick..Looks like cold karo syrup

 

As in my first response... an under-drained/over-filled tank usually blows the cap off but I think you've discovered the other potential result.

The aeration as mentioned, is normal.

 

It almost looks and feels like gear oil. Which has me very curious. But it doesn't smell like it. Need to talk to my son more about that he works graveyard so will ask him tonight.

 

It very easy unless you have a manual to actually drain the wrong sump and put oil in the wrong hole. The big cruiser oil drain sump looks like the transmission.

 

There is no sump drain on a sportster... the (only) drain plug on the bottom drains the shared primary-transmission. The oil tank drain on the rubbermounts is a plastic plug on the end of a hose running down from the oil bag. You can't drain the half quart or so left in the bottom of the crankcase with a normal oil change procedure... it would need to be sucked out somehow.

 

I'm having this same problem with my '07 sportster too. I noticed when my oil was just barely marking on the stick I never had this problem. It wasn't until I decided to bring the level up to the owners manual directions that this began to happen. I let a mechanic in town who has a very good reputation look at it and he said he couldn't figure it out either. But he hardly ever works on sporters.

 

Check the oil when hot, immediately after a ride. Keep the level slightly below the FULL mark, not all the way up to it. NEVER fill up to the full line after the engine has cooled and the oil in the tank has drained to the engine sump.
On pre-2004 models, the Sportster should be level for checking. 2004 and newer, the Sportster should be leaning on the jiffy stand. When in doubt, read the directions in the owner's manual.

 

I will ride the bike until it's fully warmed up, drain the oil and have always refilled with 3 qts of oil. That puts the oil level right at the full mark every time, and I've never had any issues with oil blowing out of the tank, in the airbox, or coming out the crankcase breather vent tube that I have run under the bike.

I will sit on the bike and slowly rock it side to side to get as much oil out of the tank as possible, not that all that much more comes out though.

 

Yes, drain the oil as soon as you shut the engine off while the oil tank is at its maximum capacity. This is more important than rocking the bike side-to-side which may not get anymore oil out, like it does when you drain the primary. When I change my oil and oversize filter (same diameter as stock but longer - made by WIX) I only have to add 2.8 quarts to reach the full mark, so I drain a couple ounces when I "burp" the oil drain hose to get the level lower. (Burping the oil drain hose gets the air bubble out that can cause cavitation in the oil pump.)

 

I'll get maybe a cup or so more out of the oil tank. Like I said not much. I lean the bike to the right as far as I can still comfortably hold it for 15-20 seconds a couple of times, and then lean it back over onto the sidestand.