Bashby suggested it might have a view window too, so with two of you mentioning it I looked and found it. I also looked at the owners manual again and didn't see any mention of it. ?????????????? Not very good product documentation, in my opinion. Another problem is that the glass looks like it's smokey, i.e., not transparent, so I can't see through it. But it does have markings on the case near the non-transparent view window showing where the oil level should be. I took out the dipstick, measured from the top of the case to the markings, and used that measurement on the dipstick to see if the oil level is ok, and it is. I saw the cat pump oil you mentioned when I looked at the Northern website. Seems odd that I wouldn't be able to buy stuff like that locally, but at least I now know what to get and where to get it from, so thanks.