How much oil does a Mercury 4 / 5 / 6 FourStroke take?

Either 15 fl oz or 450 ml. No oil filter.

What engine oil does a Mercury 4 / 5 / 6 FourStroke use?

Quicksilver 4-Cycle Marine Oil, SAE 10W-30 for all temperatures; SAE 25W-40 may be used above 40 °F (4 °C). If not available, a premium 4-cycle engine oil meeting API SH, SG, SF, CF-4, CE, CD or CDII.

What gear oil does a Mercury 4 / 5 / 6 FourStroke use, and how much?

Quicksilver Gear Lube-Premium Blend. Quantity: 195 mL; Fill until lubricant appears at the vent hole.

What spark plug does a Mercury 4 / 5 / 6 FourStroke use?

NGK DCPR6E, qty 1 (hex 5/8 in, 16 mm). Gap: 0.035 in (0.9 mm).

How often should a Mercury 4 / 5 / 6 FourStroke be serviced?

The factory schedule lists: Every 100 hours of use or once yearly, whichever occurs first. 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 4 / 5 / 6 FourStroke?

The factory schedule says to replace it at 100 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 Mercury 4 / 5 / 6 FourStroke?

1300 ± 50 rpm out of gear; 1100 ± 50 rpm in forward gear. WOT: 4/5 (1999 and 2000) 4500 to 5500 rpm; 4 Bodensee (2001 and newer) 3500 to 4500; 5 Bodensee (2001 and newer) 4250 to 5250; 6 Bodensee (2001 and newer) 5000 to 6000.

Mercury 4 / 5 / 6 FourStroke (1 cylinder 123 cc, model year 1999 on, serial 0R000001 to 0R411837) service guide

Oil, gear oil, spark plugs and the service schedule for the Mercury 4 / 5 / 6 FourStroke (1 cylinder 123 cc, model year 1999 on, serial 0R000001 to 0R411837) (4 to 6 hp, four-stroke), from the factory service manual, plus how we service it in Hawaiʻi.

Models covered: Mercury 4, 5 and 6 FourStroke, starting model year 1999, serial 0R000001 to 0R411837. the ending serial is where the next manual starts (0R411838). 1 cylinder, over head valve, 7.5 cu in (123 cc), carbureted, manual start, no oil filter. Gear ratio 2.15:1.

Quick answers

How much oil does a Mercury 4 / 5 / 6 FourStroke take?: Either 15 fl oz or 450 ml. No oil filter.
What engine oil does a Mercury 4 / 5 / 6 FourStroke use?: Quicksilver 4-Cycle Marine Oil, SAE 10W-30 for all temperatures; SAE 25W-40 may be used above 40 °F (4 °C). If not available, a premium 4-cycle engine oil meeting API SH, SG, SF, CF-4, CE, CD or CDII.
What gear oil does a Mercury 4 / 5 / 6 FourStroke use, and how much?: Quicksilver Gear Lube-Premium Blend. Quantity: 195 mL; Fill until lubricant appears at the vent hole.
What spark plug does a Mercury 4 / 5 / 6 FourStroke use?: NGK DCPR6E, qty 1 (hex 5/8 in, 16 mm). Gap: 0.035 in (0.9 mm).
How often should a Mercury 4 / 5 / 6 FourStroke be serviced?: The factory schedule lists: Every 100 hours of use or once yearly, whichever occurs first. 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 4 / 5 / 6 FourStroke?: The factory schedule says to replace it at 100 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 Mercury 4 / 5 / 6 FourStroke?: 1300 ± 50 rpm out of gear; 1100 ± 50 rpm in forward gear. WOT: 4/5 (1999 and 2000) 4500 to 5500 rpm; 4 Bodensee (2001 and newer) 3500 to 4500; 5 Bodensee (2001 and newer) 4250 to 5250; 6 Bodensee (2001 and newer) 5000 to 6000.

Maintenance specs

Engine oil	Quicksilver 4-Cycle Marine Oil, SAE 10W-30 for all temperatures; SAE 25W-40 may be used above 40 °F (4 °C). If not available, a premium 4-cycle engine oil meeting API SH, SG, SF, CF-4, CE, CD or CDII
Engine oil quantity	Either 15 fl oz or 450 ml. No oil filter
Engine oil drain plug	Lubricate the seal on the drain plug with oil and reinstall
Gear lube	Quicksilver Gear Lube-Premium Blend
Gear lube quantity	195 mL; Fill until lubricant appears at the vent hole
Gear lube fill/drain and vent plugs	1 fill/drain plug ("OIL") and 1 vent plug ("OIL LEVEL"), each with a sealing washer (2 plugs, 2 gaskets in the parts list).
Spark plug	NGK DCPR6E, qty 1 (hex 5/8 in, 16 mm)
Spark plug gap	0.035 in (0.9 mm)
Spark plug torque	13 lb-ft (17.5 Nm); or finger tight then 1/4 turn
Idle speed	1300 ± 50 rpm out of gear; 1100 ± 50 rpm in forward gear. WOT: 4/5 (1999 and 2000) 4500 to 5500 rpm; 4 Bodensee (2001 and newer) 3500 to 4500; 5 Bodensee (2001 and newer) 4250 to 5250; 6 Bodensee (2001 and newer) 5000 to 6000
Thermostat	Opens at 122 to 129 °F (50 to 54 °C); full open 145 to 153 °F (63 to 67 °C); valve lift minimum 0.12 in (3 mm)
Fuel line filter	Inspect the fuel line filter; if it appears to be contaminated, remove and replace.
Anodes	One zinc anode on the gear case, bolt 70 lb-in (8 Nm)
Valve clearance, cold	Intake 0.002 to 0.005 in (0.06 to 0.14 mm); exhaust 0.004 to 0.007 in (0.11 to 0.19 mm)

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.

Every 100 hours of use or once yearly, whichever occurs first

Replace: engine oil, oil drain plug gasket, gear case oil, gear case plug gaskets, water pump impeller

Check: spark plugs, fuel filter, anodes
Every 200 hours or 1 year (our Hawai‘i yearly service) Hawai‘i

Replace: engine oil, oil drain plug gasket, gear case oil, gear case plug gaskets, water pump impeller

Check: spark plugs, fuel filter, anodes

Source: Mercury 4/5/6 FourStroke service manual, 90-857138R02. Specs can change by model year and serial number, so always confirm your exact model from the serial tag on the clamp bracket.

Mercury 4 / 5 / 6 FourStroke (1 cylinder 123 cc, model year 1999 on, serial 0R000001 to 0R411837) service guide

Quick answers

Maintenance specs

Service schedule

Every 100 hours of use or once yearly, whichever occurs first

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

Other Mercury guides