The reasons why diesel antiwear agent doesn't work are engine oil problem and engine problem.

1. Oil problem: the matching problem between diesel oil antiwear agent and diesel oil, such as poor quality and high water content of diesel oil, will affect the effect of diesel oil antiwear agent.

2. Engine problems: diesel engine's own problems, such as serious wear or failure of cylinder liner, piston ring, piston, crankshaft and other parts, will lead to the failure of diesel engine anti-wear agent.