Simple division for sinking funds: 24 months — This answer is a straightforward arithmetic demonstration of how sinking funds work. If the target cost is $3,600 and you set aside $150 per month, dividing the target by the monthly contribution gives the time until the goal is reached: 3600 ÷ 150 = 24 months. Sinking funds reduce the pain of large, irregular expenses by turning them into small, repeatable habits. The calculation is deliberately simple so you can plug in different targets and contributions to find the schedule that fits your cash flow. The mental accounting value is high: labeling money for a specific purpose increases discipline and reduces impulse spending that would otherwise derail the plan. Use round, payroll-friendly contributions when possible to make automation easy.

Practical tips for implementing the plan — Once you know the months required, automate a monthly transfer of $150 into a dedicated “Car Repair” or “Sinking Fund” account. Track progress visually (spreadsheet, app, or calendar) and treat any windfalls as optional accelerators rather than the primary funding path. If your timeline is too long, consider increasing the monthly contribution slightly or finding small recurring expenses to trim. Conversely, if $150 feels unaffordable, extend the timeline or combine the sinking fund with short-term income increases (freelance work, side gigs) so the core emergency fund remains intact. Keep this money liquid but separate from everyday checking to reduce temptation.