Define the avoidable cost
Enter only the oil, labour and disposal costs that would actually change under the proposed maintenance plan. Do not include OEM filters or inspections that remain necessary. Top-ups that continue unchanged belong in neither the claimed saving nor an extended-drain multiplier.
Include the filtration programme
Add equipment and installation costs, then annual cartridges, analysis, pump energy and additional service labour. Include incremental costs for the same machines and period as the baseline. Use one currency and a consistent VAT-exclusive basis.
Keep opportunity value separate
The calculator reports avoided downtime as a separate scenario value, excluded from cash payback. If staffing or production costs do not actually change, treating those hours as cash exaggerates the return.
Interpret the result
Simple payback equals initial investment divided by positive annual net cash benefit. A non-positive benefit has no positive cash payback in this model. This is an undiscounted steady-state estimate: financing, taxes, escalation, residual value and unplanned failure benefits are excluded. Validate inputs and interval assumptions before investment.