What Scoby4wd wrote, regarding fractional turning + what I wrote about heating. idosubaru also, the penetrant won't get through all the crud, if they are really bad. The reason the heat helps so much is that aluminum expands more than steel at the same temperature. Rust & corrosion expand, that's why they get stuck in the first place. Keeping within normal operating temperatures means seal, etc. are not damaged, along with metal characteristics.