I have owned my bike for about a month now and I wanted to check the oil. I warmed my bike up for about 5 minutes let sit for another 5 minutes and I still can't see any oil through the window. I also took the cap off and cannot see a drop of oil down in the motor. I have also had issues with very rough shifting. Is it possible that the previous owner had zero oil in the bike?

 

Did you check it with the bike straight up?

 

Yep, had someone stand it up for me and still nothing

 

Lean it a bit to the right and look for some kind of reading. If you see some, top it off to the correct level.

Since its new to you, why not change it anyway? That way you know when it was done, how much is in it, and what oil is used.

 

Definitely change the oil! That way you can get an idea of how much was in there but also you can make sure that the correct amount is in when you refill. It's always better to have a little too much than a little too little! I think those windows are similar to the rear axle hash marks when adjusting your chain, i.e. a very general guideline. My first bike was a Ninja 300 and the proper amount of oil showed at 3/4 of the way up in the window. My current F4i shows a little above the very top of the window so every bike is different and knowing where yours should be is a good thing!