RE: After run oil
I have lived in Mytle Beach, SC; Miami, FL; and Georgia. Many of these climates has a lot of 100% humidity. Been modling since the late 60's and R/C since the mid 70's and have never had a rusted bearing except for a set left in a parts bin. Don't think I have ever heard of a bearing rusting until synthetic oil hit was used. And about the same time people started pouring oil in their engines. I think the secret is to use plenty of castor oil, that varnish protects the engine from rust.