STP Carb Spray Cleaner: Cleans carburettors, linkages and automatic chokes. STP stands for Scientifically Treated Petroleum. Formed in 1954 in the United States the company has a strong history with motor racing that has allowed it to demonstrate the high quality nature of its products. Engines, from motor vehicles to boats and even lawn mowers all are affected by grease, grime, oil and dirt deposits. These small but significant elements can all build up to affect the performance of the engine itself.