. Stp. Professional series carb spray cleanercleans carburettors, linkages and automatic chokes. Stp professional heavy duty carb spray cleaner is designed to quickly remove gum, sludge, varnish, grease and dirt from carburettors linkage and automatic chokes. Regular usage will ensure prevention of dirt build up. . Directions. With engine cool or only slightly warm, begin clean up. For carburettor and carburettor linkage: remove air cleaner and apply stp carb spray cleaner to entire exterior surface of the carburettor, including the linkage and choke (valve) shaft. Allow to soak for a minute and then re-apply to thoroughly remove dirt, grease and deposits. For automatic chokes: to thoroughly clean the automatic choke, spray both ends of the choke valve while opening and closing it by hand. Then spray vacuum cylinder to remove dirt and gum. Start the engine and apply stp carb spray cleaner in bursts around inside of carburettor throat to remove deposits from throttle plate area and other parts. . Is it safe to use in my vehicle. Stp professional carb spray cleaner is suitable for vehicles with carburettor, carburettor linkage and automatic chokes. Take note. Wash off immediately if sprayed on car finish. Can cause wax and paint streaking.