I find the answer pretty interesting as I've heard this discussion in my own club. I've always used after run oils myself but I tend to use much more of it then I see being used in my club. I have never had a rust problem. Typically I see others using no ARO or a couple of drops and I guess they figure that is sufficient. I don't know how much you use or how you distribute it but a rusty bearing seems to me to be bound to happen if you live in a humid climate, you don't burn your fuel out, and don't use enough ARO. I can understand O.S.'s position. Rust surely isn't a defect in manufacture unless delivered new in that condition. I'd hate to pay them to change the bearings when you can do so yourself for much less, I've done it for many people. I guess in the end you have to decide what it's worth to you. Hope it all works out.