Zero-turn mowers are expensive pieces of equipment, and they take more maintenance than a standard push mower. But a consistent maintenance schedule keeps them running for years and prevents the most common failures. Here's what to do and when.
Before Every Mow (2 Minutes)
- Check the engine oil — pull the dipstick, wipe it, reinsert, pull again. The oil should be between the full and add marks. If it's low, top it off with the oil weight specified in your manual (typically SAE 30 or 10W-30).
- Check the tire pressure — zero-turns are sensitive to uneven tire pressure. If one rear tire is low, the mower will pull to that side and leave an uneven cut. Check all four tires and inflate to the pressure on the sidewall (typically 13–15 psi for rear, 20+ for front casters).
- Clear debris from the deck and engine cooling fins. Grass buildup on the engine causes overheating.
Every 25 Hours or Monthly
1. Check the Hydraulic Oil Level
Zero-turn mowers use hydraulic pumps and wheel motors to drive the rear wheels. The hydraulic system has its own oil reservoir — separate from the engine oil. Check the hydraulic oil level monthly:
- Locate the hydraulic reservoir (usually near the rear of the frame)
- Check the sight glass or dipstick
- Top off with the specified hydraulic oil if low
- Look for leaks around the pumps and wheel motors — a slow leak will eventually leave you stranded
2. Clean the Air Filter
A clogged air filter reduces power and fuel economy. Remove the filter and check it:
- Foam pre-filter: Wash in soapy water, rinse, dry, and re-oil with filter oil
- Paper main filter: Tap gently to remove loose dirt. If it's dark or oily, replace it. Never wash a paper filter.
3. Grease the Spindles and Front Casters
Most zero-turns have grease fittings on the blade spindles and front caster wheels. Pump grease into each fitting until you see clean grease emerge. Use a lithium-based grease — the type specified in your manual.
Neglecting the grease fittings is the #1 cause of spindle bearing failure. A seized spindle costs $100+ and leaves the mower out of commission.
4. Check the Deck Belt
Inspect the deck drive belt for cracks, glazing, or wear. A worn belt slips, reduces blade speed, and leaves a ragged cut. Replace it if you see any damage — don't wait for it to break.
Every 50 Hours or Twice per Season
1. Change the Engine Oil and Filter
Change the engine oil while it's warm so it flows freely. Replace the oil filter at the same time. Use the oil weight and filter specified in your manual.
2. Replace the Air Filter
Even with regular cleaning, the paper air filter needs replacement every 50 hours. A fresh filter restores full power and fuel economy.
3. Replace the Fuel Filter
A clogged fuel filter starves the engine and causes surging or power loss. Replace it annually — it's a $5 part.
4. Replace the Spark Plug(s)
Most zero-turn engines have one or two spark plugs. Replace them every 100 hours or once per season. Gap them to the spec in your manual (typically 0.030").
Every 100 Hours or Annually
1. Change the Hydraulic Oil and Filter
The hydraulic system needs an oil change just like the engine. Drain the old hydraulic oil, replace the filter, and refill with the specified oil. This is often overlooked and leads to pump failure — a $500+ repair.
2. Sharpen or Replace the Blades
Dull blades tear grass instead of cutting it, leaving ragged tips that turn brown and invite disease. Sharpen the blades every 25 hours, and replace them when they're worn or unbalanced. An unbalanced blade causes vibration that damages the spindle bearings.
3. Service the Deck
Remove the deck and clean it thoroughly. Inspect the spindle bearings for play, check the belt tension, and lubricate all fittings. This is also a good time to check the deck for cracks or weld failures.
Before Winter Storage
- Add fuel stabilizer and run the engine for 10 minutes
- Change the engine oil so old oil doesn't sit in the crankcase all winter
- Remove the battery and store it indoors on a maintainer
- Grease all fittings so they don't seize during storage
- Clean the deck and spray it with a rust preventative
- Store indoors or under a fitted cover
The Bottom Line
Zero-turn maintenance comes down to three things: keep the oil clean, keep the grease fittings greased, and keep the hydraulic oil fresh. Do those three things and your zero-turn will outlast your neighbor's.