An internal combustion engine monitoring system can include a fluid filter disposed between at least one fluid inlet of the internal combustion engine and at least one of a fluid source or an ambient fluid environment. At least one fluid sensor arranged can be arranged to detect a plurality of indications of respective fluid pressures on first and second sides of the fluid filter at a plurality of corresponding engine operating conditions. The indications can be compared with their corresponding operating conditions to assess a condition of the fluid filter and estimate a lifetime thereof.