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Mercury OptiMax 200 / 225 / 250 (3.0 L, including DTS, 2005 on) service guide

Oil, gear oil, spark plugs and the service schedule for the Mercury OptiMax 200 / 225 / 250 (3.0 L, including DTS, 2005 on) (200 to 250 hp, two-stroke), from the factory service manual, plus how we service it in Hawaiʻi.

Models covered: Mercury 200, 225 and 250 OptiMax direct fuel injection 2-stroke, 60° V6, 3.0 liter, including Digital Throttle and Shift models, model year 2005 and newer, serial 0T985587 and above. Two gear housings: gear housing S/N 1B504988 and below, and S/N 1B504989 and up; the gear lube amount differs.

Quick answers

What two-stroke oil does a Mercury OptiMax 200 / 225 / 250 use?
OptiMax 2-Cycle Outboard Oil or TC-W3 Premium Plus; Engine reservoir 0.84 liter (0.88 US qt); external tank 11.4 liter (12 US qt).
What gear oil does a Mercury OptiMax 200 / 225 / 250 use, and how much?
Mercury or Quicksilver High Performance Gear Lubricant. Quantity: Gear housing S/N 1B504989 and up: 970 ml (32.8 fl oz). Gear housing S/N 1B504988 and below: 800 ml (27 fl oz); "approximately 798 ml (27 fl oz)".
What spark plug does a Mercury OptiMax 200 / 225 / 250 use?
200 and 225: NGK IZFR5G, gap 0.8 mm (0.031 in). 250: NGK IZFR6J, gap 1.06 mm (0.042 in); qty 6.
How often should a Mercury OptiMax 200 / 225 / 250 be serviced?
The factory schedule lists: Every 100 hours or once a year; Every 300 hours or three 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 Mercury OptiMax 200 / 225 / 250?
The factory schedule says to replace it at 300 hours. In Hawaiʻi's warm salt water we replace it every 200 hours or 1 year, whichever comes first, because a worn impeller is the most common cause of overheating.
What is the idle speed of a Mercury OptiMax 200 / 225 / 250?
650 ± 25 RPM. WOT 5000 to 5750 RPM (200, 225), 5500 to 6000 RPM (250).
What is the propeller nut torque on a Mercury OptiMax 200 / 225 / 250?
75 N·m (55 lb·ft); bend three tabs of the retainer into the thrust hub grooves.

Maintenance specs

Injection oilOptiMax 2-Cycle Outboard Oil or TC-W3 Premium Plus; Engine reservoir 0.84 liter (0.88 US qt); external tank 11.4 liter (12 US qt)
Gear lubeMercury or Quicksilver High Performance Gear Lubricant
Gearcase capacityGear housing S/N 1B504989 and up: 970 ml (32.8 fl oz). Gear housing S/N 1B504988 and below: 800 ml (27 fl oz); "approximately 798 ml (27 fl oz)"
Fill and vent screws6.8 N·m (60 lb·in), both gear housings; replace the sealing washers if damaged
Gearcase leak test69 to 83 kPa (10 to 12 psi) for 5 minutes, both gear housings
Spark plug200 and 225: NGK IZFR5G, gap 0.8 mm (0.031 in). 250: NGK IZFR6J, gap 1.06 mm (0.042 in); qty 6
Spark plug torqueFinger tight plus 1/4 turn, or 27 N·m (20 lb·ft)
Idle speed650 ± 25 RPM. WOT 5000 to 5750 RPM (200, 225), 5500 to 6000 RPM (250)
ThermostatStamped 130°; starts to open 58.8 °C (138 °F); fully open 69.4 °C (157 °F); piston height at full open at least 3.962 mm (0.156 in)
Fuel filterReplace every 100 hours or once a year (water separating filter under a cap; removal tool 91-896661). Lubricate the O-ring seals with oil; squeeze the primer bulb firm and check for leaks
AnodesAnode plate screw 54 N·m (40 lb·ft), both gear housings. Gearcase side anode screw (M6 x 40) and nut 8 N·m (71 lb·in) on the S/N 1B504988 and below gear housing; the torque is left blank for the 1B504989 and up gear housing
Propeller nut75 N·m (55 lb·ft); bend three tabs of the retainer into the thrust hub grooves
Power trim fluidPower Trim and Steering Fluid; if not available, automotive ATF. Showa trim maximum leak-down 55 mm (2.2 in) in 24 hours. Fluid level even with the bottom of the fill hole, tilted full up
Alternator beltInspect every 100 hours or once a year; replace if cracked or deteriorated, rough or uneven, or worn on the edges or outer surfaces.

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. Every 100 hours or once a year

    Replace: fuel filter, spark plugs, gear case oil, gear case plug gaskets

    Check: air filter, anodes

  2. Every 200 hours or 1 year (our Hawai‘i yearly service) Hawai‘i

    Replace: fuel filter, gear case oil, gear case plug gaskets, water pump impeller

    Check: air filter, spark plugs, anodes

  3. Every 300 hours or three years

    Replace: fuel filter, gear case oil, gear case plug gaskets, water pump impeller, fuel return filters

    Check: air filter, spark plugs, anodes

We replace the water pump impeller at every service from 200 hours up, which can be sooner than the factory schedule, because of Hawaiʻi’s warm salt water.

Source: Mercury 200/225/250 OptiMax Direct Fuel Injection including Digital Throttle and Shift service manual, 90-856252T00. Specs can change by model year and serial number, so always confirm your exact model from the serial tag on the clamp bracket.

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