I have 2 bottles of Auto-Rx left from a purchase I made in 2005. I recently purchased 5 more bottles and it seems much thinner. The older stuff feels like 100wt (like old STP) while the newer stuff feels like 5w30 motor oil. Frank says its because the new bottler has inside storage but my 2 old bottles have been stored indoors since 2005. Today I placed one in hot water to thin it before application and it didn't thin very much. Has anybody else noticed this? What do you think?