Gasoline detergents: What are they and what do they do? | Fuel Tips

The inside of your engine can become a dirty, nasty place, and those carbon deposits don’t do anything to help performance. Much of the blame for the mess goes to the hydrocarbons–the building blocks of petroleum products–fed to the engine on a daily basis. 

Blame the gum found in gasoline; blame oily vapors from the crank-case ventilation system. Either way, when these hydrocarbons get hot, instead of simply burning, they can form carbon deposits via the coking process. 

Always using a Top Tier gas, notes Zachary J. Santner, manager of product engineering and business optimization at Sunoco, will help keep those deposits at bay. But as an engine ages, he continues, the oil from aging valve seals and the crankcase vent system can still lead to deposits. 

Short of disassembling the engine and bead-blasting away the carbon, you can take measures to keep the inside of your engine clean–and that’s with detergents. Three nitrogen-based detergents are often found in gasoline and fuel additives as they’re effective at scrubbing away carbon. 

• Polyisobutylene (PIB), commonly found in gasoline and fuel additives, can prevent carbon from forming, helping keep a clean engine clean. However, it won’t really remove existing deposits. 
• Polyisobuteneamine (PIBA), also often found in fuel and additives, can actually remove some deposits. It can’t survive the temperatures of the combustion chamber, though, so think of it as limited to the injectors, intake valves and intake ports. 
• Polyetheramine (PEA), more commonly found in fuel additives and specialty race fuels, remains stable in the heat of the combustion chamber, allowing it to do more cleaning. Of course, there’s a downside: PEA costs more than the other detergents. How to find an additive containing PEA? Some quick internet sleuthing can usually reveal what’s inside a product, Santner notes.

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