Today I decided to take a ride to make sure the bike was still running well. I am currently at college and try to run the bike at least one or two times a week to make sure it doesn't sit (also gives me an excuse to go riding through the Adirondacks for an hour or so). When I started the bike up it smoked a bit more than the normal amount, and I chalked it up to the temperature being around 30 -35 degrees Fahrenheit. While riding I noticed that the normal noises slowly, but continuously, got louder. When I parked the bike I looked at the oil sight glass and saw nothing. While riding I did not have any idiot lights going off, I  was monitoring it closely since the noise was up from what I normally have heard. I checked 30 minutes later (to give it plenty of time to flow back down) and found only a small amount at the bottom of the sight glass. Looking through the oil fill hole I could only see a tiny amount at the bottom of the case. I always check my oil level before riding and today it was about 2/3rds of the way between the middle dot and the top of the sight glass. The bike normally consumes only about 4-5 ounces over 5 thousand miles, from my experience (two oil changes). I did check the oil drain screw and that was completely dry so I do not believe that the oil leaked out of there. 

I am wondering if anyone else has had a sudden consumption of oil with a cold spell. My current plan is to pick up some Marvel Mystery oil to mix in and refill the oil to the top of the sight glass. 

Thank you for any advice you can give.

I don't know whether this is the case. But what can happen is that water and fuel can contaminate the oil when slow running around town the lower engine temperature allow it to build up. When you go on a longer ride at higher speeds and longer distances the engine gets up to a higher temperature. At the higher temperatures this water fuel mix with evaporate off making it look like your oil consumption has drastically risen. Top the oil up and go for a long hard ride or give it an oil change and go for a long hard ride and it should have settled down.
Regards Martin.

It's rare but sometimes K bikes will occasionally "hide" oil that magically reappears.

I'd fill it to the half-way DOT in the sight glass and keep an eye on it.

A slight unevenness to the ground and the bike leans a touch more and the oil level can be very different, just keep an eye on it.

When you look at the engine in profile, with oil at the bottom of the sight glass, there is actually a lot of oil in there, regardless of the appearance from the filler hole.

Coolant might be leaking into the oil, which evaporated during the ride.

Or fuel. Remove the vacuum hose from the rear cylinder at the throttle body assembly. If there are signs of fuel, the fuel pressure regulator is leaking. Don't crank the engine if you suspect this,  it could do damage, unless you disable the coils and remove the spark plugs. Be prepared for something shooting out. 

Regarding the smoke, black points to rich(fuel) blue(oil) white(water)

I'm interested in the noise. My moto is ridden until salt is on the road and that can mean riding in temperatures from 15ºF up for a month or so. There is no increase in engine noise at temperature below freezing but shifting can be stiff for a half a mile or so.

When was the last oil change, which grade of oil did you use and what brand of filter did you install?

Currently, I am running 15W-50 oil in the motorcycle as the manual has the operating temperature for that weight being from -20 to 30 celsius or -4 to ~85 Fahrenheit. I used a BMW filter for my last oil change since the PO supplied me with a couple of them, I did my last oil change about 3 weeks ago. I did make sure to check the sight glass while the bike was on level ground on the center stand. I will be refilling the oil level to halfway as suggested and will ride the bike tonight or tomorrow and report back with my findings. I don't think the coolant is leaking or getting consumed as the level hasn't changed since I got the motorcycle. I will be pulling the radiator and cleaning it during my winter break as well as touching up a few other things that I didn't want to mess with during the main riding season.

Did you run the bike after the oil and filter change to recheck the oil?

Do you fill the filter before screwing it in?

I have occasionally found erratic oil consumption but keep an eye on it..

If there is coolant leaking into the oil it is very easy to tell.  Put the bike on the center right after riding it.  If there's coolant in the oil you will see froth/bubbles in the sight glass.

I did run the bike immediately after the oil change and didn't see any real drop in the sight glass level. I normally put a small amount of oil in the filter before screwing it in. I have not seen froth/bubbles after riding it.

A small amount in the filter and oil at the red dot on the glass, it will go near the bottom of the glass after you have run it.

I added 2 quarts of oil and mixed a small amount of Marvel into it. The bike is now running much better and smoked a lot less when I started it up. I took it out for a hard ride and stopped every 5 minutes or so to check that the level wasn't dropping too much. Parked it again and will be checking it in a few days with another ride weather permitting.

If you had to add 2 qts of oil to the crankcase, then it was really down.  I can't see how the engine would use that amount of oil in the short amount of time you are talking about.

That would explain the noises you where hearing, lack of oil.  Something doesn't add up as adding Marvel to the crankcase wouldn't change much of anything.  It is basically a solvent, so you will want to dump the oil & filter after a short period of time.  It works similar to Sea Foam and will help clean up the inside of the engine, which is not always a good thing.

Update:
Today when I went out to the motorcycle, I checked the sight glass. The oil level had increased to the point where I couldn't see the level while the bike was on its center stand. When I tipped the bike to its side stand I could see the bubble right at the top of the sight glass. I know that the oil level is higher than it should be. I don't quite understand where the excess oil was hiding and how it got back in the case. Is this oil level high enough that running the bike would likely cause damage? I am on the fence with draining the excess oil to the proper level or not as I don't know where the oil disappeared to last time. Any idvice on what I should do? I will be riding the motorcycle for a 2-hour trip next week and want to make sure it functions well during that ride.

I told you that they have a secret way of "hiding" oil.   I have no idea why/how.

Just pull the drain plug and then put it back in quickly to get a little oil out and get it down below the top line. That's what I'd do.

I have no idea how the oil in the pan actually gets to the sight glass.  I know that in the past I have done oil changes or added oil without the level in the glass changing, and then showing after the engine is run.

My experience leads me to believe that there may be air bubbles in the sight glass or behind it that may be affecting the level in the glass.  Perhaps the cold temperatures and thicker oil is preventing oil flow to the glass or encouraging the bubble.

@John A wrote:I don't quite understand where the excess oil was hiding and how it got back in the case.

The oil was in the case all along. Like .75 indicates, an air bubble was probably restricting its flow into the sight glass. That's likely the reason instructions advise running the engine first then waiting a few minutes before checking the level—to allow evacuation of air from the glass.

Do what duck suggests, ride off and leave your worry behind. In the future, fill by volume. An oil change including the filter is 3.75L in volume. Drain the oil while it's hot then refill with 3.60L and develop a new relationship with the sight glass.

A good rule of thumb is if the engine calls for 3.75 litres including filter change, at an oil change with filter, add 3 litres of oil.  Fill up the oil filter before you put it in. On the center stand, start the engine and let it run for a couple of minutes, check for leaks etc. Shut it down, clean up your used oil etc. Then have a look in the site glass. 

There are holes top and bottom in the site glass so I can't see how any air would stop oil from flowing into it.  Another thing is that the garage floor or the centerstand are not always level, so that can mess up your readings.

Don't run it with too much oil and as somebody else advised, get a clean pan for the oil, undue the drain bolt, and quickly put it back in place. That will let some oil out of the block. It will be messy doing it that way so be prepared.  In lieu of that, just drain the oil into the clean pan, and then put the right amount back in the engine.

The K series are not the only ones that hide the oil.  I owned a couple of R1100's and you had to do a bit of a dance to get an accurate reading in the site glass.  The distance between the upper and lower red lines is usually about 500 CC of oil.