Tohatsu MFS25C / MFS30C EFI (2016) service guide

Quick answers

How much oil does a Tohatsu MFS25C / MFS30C EFI take?

1.8 L (1,800 mL, 60.8 fl oz) with filter; 1.6 L without filter.

What engine oil does a Tohatsu MFS25C / MFS30C EFI use?

4-stroke engine oil, API SF, SG, SH or SJ, SAE 10W-30/40; procedure lists API SE, SF, SG, SH, SJ, SL, SAE 10W-30 or 10W-40, NMMA FC-W 10W-30.

What gear oil does a Tohatsu MFS25C / MFS30C EFI use, and how much?

Genuine gear oil or API GL-5, SAE #80-90. Quantity: 360 mL (12.2 fl oz); fill from the lower plug hole.

What spark plug does a Tohatsu MFS25C / MFS30C EFI use?

NGK DCPR6E. Gap: 0.8 to 0.9 mm (0.032 to 0.035 in); limit 1.2 mm (0.047 in).

How often should a Tohatsu MFS25C / MFS30C EFI be serviced?

The factory schedule lists: First 20 hours or 1 month; Every 50 hours or 3 months; Every 100 hours or 6 months; Every 200 hours or 1 year. In Hawaiʻi's salt water we do a full yearly service every 200 hours or 1 year, whichever comes first, and a new engine needs its first (break-in) service.

When should the water pump impeller be replaced on a Tohatsu MFS25C / MFS30C EFI?

The factory schedule says to replace it at 200 hours, and we follow that. In any case we never let it go longer than a year in Hawaiʻi's salt water.

What is the idle speed of a Tohatsu MFS25C / MFS30C EFI?

850 r/min in neutral and trolling; 850 ± 30 r/min.

What is the propeller nut torque on a Tohatsu MFS25C / MFS30C EFI?

25 N·m (18 lb·ft) [2.5 kgf·m], then split pin.

Maintenance specs

Engine oil	4-stroke engine oil, API SF, SG, SH or SJ, SAE 10W-30/40; procedure lists API SE, SF, SG, SH, SJ, SL, SAE 10W-30 or 10W-40, NMMA FC-W 10W-30
Engine oil quantity	1.8 L (1,800 mL, 60.8 fl oz) with filter; 1.6 L without filter
Oil filter	18 N·m (13 lb·ft) [1.8 kgf·m]; oil the O-ring; replace every 200 hours or 2 years
Engine oil drain bolt	24 N·m (17 lb·ft) [2.4 kgf·m], M14 x 1.5
Gear oil	Genuine gear oil or API GL-5, SAE #80-90
Gear oil quantity	360 mL (12.2 fl oz); fill from the lower plug hole
Gear oil plugs	New gaskets; attach the upper plug first.
Gear case leak test	0.069 MPa (10 psi) [0.7 kgf/cm²]
Spark plug	NGK DCPR6E
Spark plug gap	0.8 to 0.9 mm (0.032 to 0.035 in); limit 1.2 mm (0.047 in)
Spark plug torque	18 N·m (13 lb·ft) [1.8 kgf·m]
Idle speed	850 r/min in neutral and trolling; 850 ± 30 r/min
Thermostat	Starts opening 60 ± 1.5 °C (140 ± 3 °F); lift 3.0 mm (0.118 in) or more at 75 °C (167 °F); cover bolt 6 N·m (4 lb·ft) [0.6 kgf·m]
Propeller nut	25 N·m (18 lb·ft) [2.5 kgf·m], then split pin
Valve clearance, cold	Lock nut 7 N·m (5 lb·ft) [0.7 kgf·m].
Timing belt	Check for slack and wear (no deflection spec); belt tensioner bolt 27 N·m (20 lb·ft) [2.7 kgf·m]

Service schedule

The factory maintenance intervals, with what is replaced and what is checked at each. Rows marked Hawaiʻi are our shop's yearly service for salt water use.

1. First 20 hours or 1 month

   Replace: engine oil, oil drain plug gasket, gear case oil, gear case plug gaskets, propeller cotter pin

   Check: spark plugs, fuel filter

2. Every 50 hours or 3 months

   Replace: gear case plug gaskets, propeller cotter pin

   Check: fuel filter, gear case oil, water pump impeller

3. Every 100 hours or 6 months

   Replace: engine oil, oil drain plug gasket, gear case oil, gear case plug gaskets, propeller cotter pin

   Check: spark plugs, fuel filter, water pump impeller, thermostat, anodes

4. Every 200 hours or 1 year

   Replace: engine oil, oil filter, oil drain plug gasket, fuel filter, gear case oil, gear case plug gaskets, propeller cotter pin, water pump impeller

   Check: spark plugs, thermostat, anodes

Source: Tohatsu service manual 4st 25/30 2016, MFS25C/30C. Specs can change by model year and serial number, so always confirm your exact model from the serial tag on the clamp bracket.