Nitration is the chemical degradation of crankcase oil caused by the reaction of nitrogen oxides produced during the combustion process.
Low crankcase oil temperatures accelerate the rate of nitration.
In gas engines, nitration is the predominant factor that determines lubricant life.
Nitrogen oxide by-products enter the oil during normal operation because of blow-by past the compression rings.
| Causes | Effects |
| Lean burn engine operation | Accelerated oil thickening |
| Low operating temperatures | Acidic by-products are formed |
| Abnormal blow-by | Increased by-products are formed |
| improper spark timing | Increased cylinder and valve train wear |
| Faulty Crankcase ventilation | Combustion area deposits |
| Engine overload | Increased acidity in oil |
| Accelerated sludge formation |
| Recommendations |
| Increase crankcase oil operating temperatures if below 80°C |
| Check crankcase venting hose and valves |
| Ensure proper air / fuel ratio |
| Perform compression check or cylinder leak |
