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...
Quick answer: Mercury FourStroke oil capacity is not determined by horsepower alone. A 90 HP can take 4.54 L (4.8 US qt), 5 L (5.28 US qt) or 5.2 L (5.5 US qt) 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.
How to read the source: Gearcase millilitres are conversions from the guide's US fluid ounces, rounded to the nearest 5 mL. Oil grades follow the printed recommendation column; the guide allows different grades for certain temperatures and applications, so the serial-number owner's manual controls.
Ambiguous entries: The guide lists two 2001+ 40 HP 996 cc rows (14.9 and 24 US fl oz) without distinguishing their gearcases. Do not select either by horsepower alone. The 2006+ 90 HP serial range also overlaps the later 2.1 L row; identify the powerhead first. The 2018 150 Pro XS row is reproduced as printed, but its filter and gearcase must be confirmed by serial number before ordering or servicing.
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 |
990 mL (1.05 US qt) |
200 mL (6.8 US fl oz) |
| 1999-2004, 323 cc |
990 mL (1.05 US qt) |
200 mL (6.8 US fl oz) |
| 2005+, 209 cc |
790 mL (0.84 US qt) |
320 mL (10.8 US fl 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 |
4.54 L (4.8 US qt) |
665 mL (22.5 US fl oz) |
8M0162830 |
| 2006+ EFI, serial 1B366823 and up |
5 L (5.28 US qt) |
710 mL (24 US fl oz) |
877761Q01 |
| 2014+ 2.1 L, serial 2B094996 and up |
5.2 L (5.5 US qt) |
800 mL (27.1 US fl 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 litres (3.17 US quarts) of crankcase oil. Its gearcase quantity changes with the lower unit:
- Standard gearcase: 340 mL (11.5 US fl oz)
- BigFoot or Command Thrust gearcase: 710 mL (24 US fl 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 |
| 2.5-25 HP rows on guide page 24 |
Mercury 10W-30 |
| 30-60 HP rows 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.
For four-stroke engines, use oil that meets Mercury's specified marine four-stroke standard, commonly FC-W, as well as the viscosity and formula required by the exact manual. An automotive oil with the same viscosity printed on the bottle is not automatically the same specification.
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.
Two-stroke engine oil is a separate product from four-stroke crankcase oil. Use the TC-W3 oil type and Mercury product named for the exact two-stroke family.
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.
From the Shop
The avoidable mistake is usually not a bad conversion. It is matching the right horsepower to the wrong engine family or lower unit. A clear serial-label photo and a gearcase photo settle more questions than the cowl badge does.
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.
