oiltight

/ˈɔɪlˌtaɪt/
adjective
  1. Designed or sealed so that oil cannot pass through or leak out.
    • They used oiltight containers to transport the lubricant safely.
    • The engine's oiltight gasket prevented any leaks onto the garage floor.
    • The mechanic checked that all seals were oiltight before starting the machine.