Quick answer: Mercury FourStroke oil capacity is not determined by horsepower alone. A 90 HP can take 4.8, 5.28 or 5.5 US quarts depending on year, engine family and serial break. Use the lookup below to match horsepower, year, displacement, gearcase and serial number, then...
Quick answer: Mercury FourStroke oil capacity is not determined by horsepower alone. A 90 HP can take 4.8, 5.28 or 5.5 US quarts depending on year, engine family and serial break. Use the lookup below to match horsepower, year, displacement, gearcase and serial number, then confirm the final level on the dipstick and in the manual for that engine.
The label on the cowl gets you into the right neighbourhood. It does not always identify the powerhead, gearcase or serial break that sets the capacity.
That is why this lookup keeps similar-horsepower engines on separate rows. It is based on Mercury Marine's 2026 Capacity Guide, publication 8M0243459, pages 24 through 27.
Here, 2026 is the guide's publication year. It is not a claim that every row is a 2026 or current-model-year engine.
Search the Mercury FourStroke Capacity Chart
Type a horsepower, family, displacement or serial break. Examples: 9.9, 2B094996, 200 V8 or 350 Verado.
Read This Before You Pour
The listed crankcase quantity is a reference capacity, not a target to pour blindly.
- Match the exact engine family, model year, displacement and serial break.
- Follow the drain and filter procedure in the owner's manual for that serial number.
- Add less than the full listed capacity at first.
- Run the engine only with the correct cooling-water supply, then shut it down and let the oil settle as the manual specifies.
- Check the dipstick with the engine in the specified position and bring the level to the correct mark.
- Check the filter, drain plug and sealing surfaces for leaks.
Filter changes, incomplete draining, engine angle and residual oil can change how much oil is required to reach the mark. Overfilling is not extra protection.
Why the Same Horsepower Can Have Different Capacities
Mercury has used the same horsepower badge across different powerheads and gearcases.
A 9.9 HP example
The chart lists three 9.9 HP FourStroke groups:
| Year and engine |
Crankcase |
Gearcase |
| 1995-1998, 232 cc |
1.05 qt / 0.99 L |
6.8 oz |
| 1999-2004, 323 cc |
1.05 qt / 0.99 L |
6.8 oz |
| 2005+, 209 cc |
0.84 qt / 0.79 L |
10.8 oz |
The newest row takes less crankcase oil but more gear lube than the older rows. "Mercury 9.9" is not enough information.
A 90 HP example
The serial break matters even within the same model year:
| 90 HP family |
Crankcase |
Gearcase |
Oil filter |
| 2006 EFI, serial 1B366822 and below |
4.8 qt / 4.54 L |
22.5 oz |
8M0162830 |
| 2006+ EFI, serial 1B366823 and up |
5.28 qt / 5 L |
24 oz |
877761Q01 |
| 2014+ 2.1 L, serial 2B094996 and up |
5.5 qt / 5.2 L |
27.1 oz |
8M0162830 |
That is a three-way capacity split behind one cowl number.
A 60 HP gearcase example
The 996 cc 60 FourStroke is listed at 3.17 US quarts, or 3 litres, of crankcase oil. Its gearcase quantity changes with the lower unit:
- Standard gearcase: 11.5 oz
- BigFoot or Command Thrust gearcase: 24 oz
If the gearcase is not identified, the lower-unit fill quantity can be off by more than two to one.
Which Mercury Crankcase Oil?
The capacity guide groups oils by engine family, not by one universal rule.
| Engine group in the guide |
Listed oil family |
| Most 2.5-30 HP FourStrokes |
Mercury 10W-30 |
| Most 40-60 HP FourStrokes and legacy 1.7 L 75/90/115 |
Mercury 25W-40 |
| 2.1 L 75/90/115, 150 EFI and current 3.4 L V6 / 4.6 L V8 |
Mercury 10W-30 Synthetic Blend |
| Legacy 4- and 6-cylinder Verado families |
Mercury 25W-40 |
| 2022+ V10 350/400 Verado |
Mercury 25W-40 Synthetic Blend |
| 400R |
Mercury 25W-50 High Performance Blend |
| 600 V12 Verado |
Mercury 10W-30 Full Synthetic |
Mercury includes temperature, manual-start and high-performance footnotes in its chart. Treat the table as a lookup aid, then use the viscosity and formula named in the exact owner's manual.
Which Mercury Gear Lube?
The 2026 guide generally assigns:
- Mercury 80W-90 Premium Gear Lube to the standard outboard rows below 75 HP
- Mercury SAE 90 High Performance Gear Lube to the 75 HP-and-up rows
- Mercury 85W-90 Extreme Performance Gear Lube to the V10 Verado and 400R rows
Gearcase design still controls the answer. Racing, Sport Master, counter-rotation, Command Thrust, Jet and other applications cannot be selected from horsepower alone.
What About Two-Stroke Mercury Outboards?
The same 2026 Mercury guide separates two-stroke oil by engine type:
| Engine type |
Mercury's listed oil |
| Conventional carbureted and EFI two-strokes |
Premium 2-Stroke as the good/better option, Premium Plus as best |
| OptiMax, DFI and Pro XS two-strokes |
Premium Plus as the good/better option, OptiMax/DFI oil as best |
It does not provide one universal two-stroke gearcase capacity table. Use the manual for the exact serial number.
The Five Details That Prevent a Wrong Fill
Have these in front of you before buying oil, a filter or a service kit:
- Model or horsepower
- Serial number
- Model year or production range
- Displacement or engine family
- Standard, BigFoot, Command Thrust, Verado, Sport Master or other gearcase
A photo of the transom-bracket label is usually more useful than a photo of the cowl.
Sources and Scope
The Mercury guide says its capacities are based on information believed accurate at publication and tells owners to verify against the engine owner's manual. This HBW lookup preserves the model, year and serial distinctions instead of turning them into a single horsepower rule.
Need the Right Service Scope?
If you can bring the boat to HBW in Gores Landing, submit a request at hbw.wiki/service with a photo of the engine label and the current hours. We will build the service scope from the exact engine and its documented history.
