OS55HZ not used much - getting rust.

[srhadden]

It sits for few weeks or more at a time. I took off the back plate and there is some rust. I can't tell if the bearings are notchy, they don't look rusty.

The engine seems to be running fairly well.

Should I take it out and inspect it, or just leave it alone if it's starting and running? I remember back when I was flying very often that the stock bearngs on the OS50 would get pretty notchy after awhile.

I put some general after run oil in there and turned it over a few times because I don't plan to fly for awhile.

[dchekas]

Some brown discoloration is typical, even with the engine run daily.

The tell tale sign of a bad rear bearing is when the idle develops a rattle. You should discontinue use of the engine at this point and replace the bearing.

[mdu6]

Some fuels have anti-rust agents that leave a brown/orange stain over all engine internal - this may look like rust.

[Rob43]

I've run Cool Power and Magnum, both leaving reddish-brown discoloration. No real issue. Nearly new bearings in my YS 60sr already look like this.

I ran a gallon of Rotor Rage I won at a fun fly last summer, and it makes the engine look clean inside. I am using stainless steel bearings, so, I know it's not rust. Iron content is required for there to be ferrous oxide. Still, I see the discoloration like mdu6 points out.

[Dawiev]

After-run oil between flight sessions ?