HawaiiOutboard Repair
(808) 824-4380 Request service
MenuClose

Suzuki DF25 / DF30 service guide

Oil, gear oil, spark plugs and the service schedule for the Suzuki DF25 / DF30 (25 to 30 hp, four-stroke), from the factory service manual, plus how we service it in Hawaiʻi.

Models covered: Suzuki DF25 (prefix 02501F) and DF30 (prefix 03001F) four-strokes, Q, QE, QR and T versions, 3 cylinder SOHC, 597 cm³, 3 carburetors.

Quick answers

How much oil does a Suzuki DF25 / DF30 take?
3.0 L (3.2/2.6 US/Imp. qt) oil change only; 3.2 L (3.4/2.8 US/Imp. qt) with filter.
What engine oil does a Suzuki DF25 / DF30 use?
API SE, SF, SG, SH or SJ, SAE 10W-40.
What gear oil does a Suzuki DF25 / DF30 use, and how much?
Suzuki Outboard Motor Gear Oil or SAE #90 hypoid gear oil. Quantity: 230 ml (7.8/8.1 US/Imp. oz).
What spark plug does a Suzuki DF25 / DF30 use?
NGK DCPR6E (resistor type only), qty 3. Gap: 0.8 to 0.9 mm (0.031 to 0.035 in).
How often should a Suzuki DF25 / DF30 be serviced?
The factory schedule lists: Initial 20 hours; Every 50 hours; Every 100 hours; Every 200 hours. 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 Suzuki DF25 / DF30?
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 Suzuki DF25 / DF30?
850 to 950 r/min (900 ± 50); in gear approx. 850 r/min. Synchronize the carburetors before setting idle.
What is the propeller nut torque on a Suzuki DF25 / DF30?
18 N·m (1.8 kg-m, 13.0 lb-ft), then the cotter pin.

Maintenance specs

Engine oilAPI SE, SF, SG, SH or SJ, SAE 10W-40
Engine oil quantity3.0 L (3.2/2.6 US/Imp. qt) oil change only; 3.2 L (3.4/2.8 US/Imp. qt) with filter
Engine oil filter14 N·m (1.4 kg-m, 10.0 lb-ft), 3/4 turn after the O-ring touches
Engine oil drain plug13 N·m (1.3 kg-m, 9.5 lb-ft), new gasket
Gear oilSuzuki Outboard Motor Gear Oil or SAE #90 hypoid gear oil
Gear oil quantity230 ml (7.8/8.1 US/Imp. oz)
Gearcase leak test100 kPa (1.0 kg/cm², 14.2 psi)
Spark plugNGK DCPR6E (resistor type only), qty 3
Spark plug gap0.8 to 0.9 mm (0.031 to 0.035 in)
Spark plug torque18 N·m (1.8 kg-m, 13.0 lb-ft)
Idle speed, neutral850 to 950 r/min (900 ± 50); in gear approx. 850 r/min. Synchronize the carburetors before setting idle
ThermostatOperating temperature 58 to 62 °C (136 to 144 °F)
Propeller nut18 N·m (1.8 kg-m, 13.0 lb-ft), then the cotter pin
Valve clearance, coldIN and EX 0.13 to 0.17 mm (0.005 to 0.007 in); lock nut 11 N·m (1.1 kg-m, 8.0 lb-ft)

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. Initial 20 hours

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

  2. Every 50 hours

    Replace: gear case plug gaskets

    Check: fuel filter, anodes

  3. Every 100 hours

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

    Check: spark plugs, fuel filter, anodes

  4. Every 200 hours

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

    Check: fuel filter, anodes

Source: Suzuki DF25/30 service manual, 99500-89J02-01E. Specs can change by model year and serial number, so always confirm your exact model from the serial tag on the clamp bracket.

Other Suzuki guides