I just read this on a website that rebuilds carburetors: “Warning: Never spray carburetor cleaner, starting fluid, diesel starting fluid or propane into any carburetor to prime it or check for vacuum leaks . It is harmful to an engine and will remove any protective coating on any carburetor surface. Use the same gasoline you put in the tank of the vehicle or boat. Use an old fashioned oil can.” On occasion, when one of my old cars sits for months, I use a little starting fluid. Am I, inadvertently, harming my engines?