Knocking in spark-ignition internal combustion engines occurs when combustion of some of the air/fuel mixture in the cylinder does not result from propagation of the flame front ignited by the spark plug, but one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front. The fuel-air charge is meant to be ignited by the spark plug only, and at a precise point in the piston’s stroke. Knock occurs when the peak of the combustion process no longer occurs at the optimum moment for the four-stroke cycle. The shock wave creates the characteristic metallic “pinging” sound, and cylinder pressure increases dramatically. Effects of engine knocking range from inconsequential to completely destructive. Below is Top 5 best products for engine knocking problem.
Sea Foam SF16

Sea Foam is an environmentally friendly oil additive which is registered with the Environmental Protection Agency. Since it is 100% petroleum based, it will be good for both your engine and the outside surroundings.
- Liquefies gum and varnish deposits or internal engine contaminants
- For Petrol and Diesel Applications
- Cleans Injectors, Clean Car Jets, Stabilize Fuels, Contorl Moisture in Fuels, Quietens Noisy Lifters, Clean Deposits, Add Lubricity to Fuel , Lube Upper Cylinders, De-ICe & Anti Gel
Archoil AR9100

Archoil’s AR9100 oil additive is suitable for use in all diesel and gasoline engines (including Cummins, Duramax and Power Stroke).
AR9100 forms a solid boundary lubricating film that improves performance and protects engines, gearboxes and hydraulic systems.
AR9100 eliminates hard/cold start issues caused by HEUI injector misfires in 6.0L & 7.3L Power Strokes.
Liqui Moly Cera Tec Friction Modifier

ERA TEC is a high-tech ceramic wear protection product for all motor oils. CERA TEC reduces friction and wear due to ceramic compounds that withstand extremely high chemical and thermal loads. Prevents direct metal-to-metal contact, thus increasing the engine service life. The low-friction effect reduces fuel consumption in gasoline and diesel engines. CERA TEC provides wear protection for engines, transmissions, pumps and compressors. CERA TEC should be added to the oil and is self-mixing. Sufficient for 5 liters of motor oil. Provides protection up to 50,000 km. Not suitable for use with wet clutches.
Lucas Heavy Duty Oil Stabilizer

The Lucas Heavy Duty Oil Stabilizer is an oil additive that will last you for at least 2 years. It will prolong the lifespan of your existing oil, so you won’t need to get oil changes as frequently. The main benefit of the Lucas Heavy Duty Oil Stabilizer is that it reduces the oil consumption rate. This will allow your engine performance to be optimized. You’ll have more miles per gallon and virtually no more dry startups or knocking sounds.
Genuine Ford Fluid XL-3 Friction Modifier

The Genuine Ford Fluid XL-3 Friction Modifier is an oil additive recommended specifically for Ford engines. The metallic surface friction will be immediately reduced, which will expand the lifespan of your engine. Your differentials will no longer make so much noise either. All these benefits are experienced rather quickly.