Tohatsu MFS25D / MFS30D EFI service guide

Quick answers

How much oil does a Tohatsu MFS25D / MFS30D EFI take?

1.7 L (1.8 US qt) with filter; 1.5 L (1.6 US qt) without filter.

What engine oil does a Tohatsu MFS25D / MFS30D EFI use?

4-stroke engine oil, API SH, SJ or SL; SAE 10W-30 or 10W-40.

What gear oil does a Tohatsu MFS25D / MFS30D EFI use, and how much?

Tohatsu gear oil, API GL-5, SAE #80-90. Quantity: 460 mL (16 US fl oz).

What spark plug does a Tohatsu MFS25D / MFS30D EFI use?

NGK DCPR6E (equivalent).

How often should a Tohatsu MFS25D / MFS30D 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; Every 400 hours or 2 years. 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 MFS25D / MFS30D EFI?

The factory schedule says to replace it at 200 hours and 400 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 MFS25D / MFS30D EFI?

850 r/min in neutral; dead slow in forward 850 r/min.

Maintenance specs

Engine oil	4-stroke engine oil, API SH, SJ or SL; SAE 10W-30 or 10W-40
Engine oil quantity	1.7 L (1.8 US qt) with filter; 1.5 L (1.6 US qt) without filter
Oil filter	18 N·m (13 lb·ft) [1.8 kgf·m]; replace at first 20 hours, then every 200 hours or 1 year
Engine oil drain plug	24 N·m (18 lb·ft) [2.4 kgf·m], M14 x 1.5
Gear oil	Tohatsu gear oil, API GL-5, SAE #80-90
Gear oil quantity	460 mL (16 US fl oz)
Gear oil plugs	4 N·m (3.0 lb·ft) [0.4 kgf·m], M8 x 1.25
Gear case leak test	0.05 MPa (7 psi) [0.5 kgf/cm²]
Spark plug	NGK DCPR6E (equivalent)
Spark plug torque	18 N·m (13 lb·ft) [1.8 kgf·m]
Idle speed	850 r/min in neutral; dead slow in forward 850 r/min
Thermostat	Starts opening 60 °C (140 °F), 60 ± 2 °C; lift 3.0 mm (0.118 in) or more at 75 °C (167 °F); cover bolt 9 N·m (6.6 lb·ft) [0.9 kgf·m], new gasket
Cooling water pressure (reference)	850 r/min 15 kPa (2.18 psi); 1500 r/min 30 kPa (4.35 psi); 3000 r/min 60 kPa (8.7 psi); 5000 and 6000 r/min 70 kPa (10.15 psi)
Anodes	Replace at 2/3 of new size; cooling passage anode screw 2.5 N·m (1.84 lb·ft) [0.25 kgf·m] with ThreeBond 1342; anode plug 18 N·m (13 lb·ft) [1.8 kgf·m], new O-ring
Valve clearance, cold	IN 0.10 to 0.15 mm (0.0040 to 0.0060 in); EX 0.20 to 0.24 mm; lock nut 7 N·m (5 lb·ft) [0.7 kgf·m]
Timing belt	Check and replace if necessary every 200 hours or 1 year

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 filter, oil drain plug gasket, gear case oil, gear case plug gaskets, propeller cotter pin

2. Every 50 hours or 3 months

   Replace: gear case plug gaskets, propeller cotter pin

   Check: gear case oil, water pump impeller, anodes

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, anodes

4. Every 200 hours or 1 year

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

   Check: spark plugs, fuel filter, thermostat, anodes

5. Every 400 hours or 2 years

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

   Check: spark plugs, fuel filter, thermostat, anodes

Source: Tohatsu service manual 4st 25/30 2022, MFS25D/30D. Specs can change by model year and serial number, so always confirm your exact model from the serial tag on the clamp bracket.