Twist off the oil reservoir lid.
Insert a clean drinking straw into the oil reservoir until it touches the bottom.
Mark the position on the straw where the top of the filler hole is with a small piece of tape. Pull the straw out of the reservoir.
Measure the length between the mark on the straw to where the oil starts. Add oil if the fluid level is more than 1 to 1 1/2 inches below the filler hole.