Yea some hobby shops are like that. I have one up in the Towson (MD) area, most of the stuff I need, they don't stock and aren't really a help when I need it, my 2 other track I have, which are both family owned are friendly and helpful. (Pasadena and Gaithersburg MD) My local tracks and racer...
I don't have anything arrma, but for grease, I use protek premier white and blue, red and tacky grease (or Lucas oil, Mobil 1 synthetic grease) and associated green slime.
For oils, there are different brands and some brands have a different cst to weight conversion if you wanna call it that...