Honda BF90 Oil & Filter Change
Fresh oil and a new filter are the cheapest insurance for your 90 hp Honda BF90. Below is the exact oil filter that fits, a step-by-step video of the full oil change, and what else you need for the job.
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Watch: how to do it (step by step)
How to Replace Oil Filter – Honda BF90
Changing Gear Oil Honda 75/90hp Outboard
Honda BF90 Outboard Gear Oil Change & Oil Filter Replacement Guide
Tools Needed
- Flathead screwdriver (with shaved end or square-sided shaft)
- Vice grips or adjustable wrench
- Hammer
- Impact driver with 3/8 drive drag length socket (optional, for stubborn screws)
- Small tray for parts and tools
Safety
- Ensure the outboard is cool before starting work.
- Be cautious when using tools near water.
Steps
- Tilt the engine to allow complete drainage of old oil.
- Locate the drain plug at the bottom of the gear case.
- Use a flathead screwdriver or vice grips to loosen and remove the drain plug, turning counterclockwise.
- Allow all oil to drain completely.
- Clean the area around the oil fill hole and drain plug.
- Inspect the O-rings on the drain plug and oil fill cap; replace if necessary (see Tips).
- Reinstall the drain plug by hand, ensuring it's snug but not overtightened.
- Fill the gear case with new gear oil through the oil fill hole, using the recommended amount for your engine model.
- Check for leaks around the drain plug and oil fill cap.
Tips
- The Honda BF90 uses O-ring #9 1/3 0 1 – ZW 4 – 0 0 3 for the gear case drain plug.
- If O-rings are not available, plastic ones from older models or Yamaha can be used in a pinch.
Which part do I need for my Honda BF90?
For most BF90 owners the part above (18-7909) is the right choice. Price tip: the aftermarket numbers are usually noticeably cheaper than the OEM-branded box — it is the same physical part. If you need an exact match, these compatible part numbers also fit:
Show all compatible part numbers (4)
| Part number | Description | |
|---|---|---|
| 15400 | Oil filter | Find on Amazon → |
| Honda 15400-POH-305PE, 15400-PFB-007 | Oil filter | Find on Amazon → |
| Nissan 3R0-07615-0 | Oil filter | Find on Amazon → |
| Yamaha 5GH-13440-00-00 | Oil filter | Find on Amazon → |
Many of these are the same physical part under different brand numbers. Confirm against your engine plate before ordering.
Frequently asked questions
What oil filter fits a Honda BF90 (90 hp)?
The Honda BF90 uses the oil filter sold as 18-7909, plus its OEM and aftermarket cross-references (4 compatible numbers are listed above). Confirm the number against your engine's model code and year plate before ordering.
How often should I replace the oil filter on a Honda BF90?
Change the oil and filter every 100 running hours or once a season, whichever comes first (check your manual for the exact interval).
What else do I need for an oil change on a Honda BF90?
The correct grade and amount of engine oil (see the manual or the video), a new drain-plug washer, a filter wrench and a drain pan or oil extractor pump. Nothing exotic — it is standard service equipment.
What are the signs the oil is overdue on a Honda BF90?
Dark, gritty oil well past its interval, low-pressure warnings — and milky or grey oil, which means water is getting in and should be investigated immediately.
How long does an oil change take on a Honda BF90?
About an hour for a competent DIYer. Run the engine warm first — warm oil drains faster and carries more contaminants out with it.
Related guides
- Honda BF40 oil filter
- Honda BF150 oil filter
- Honda BF200 oil filter
- Honda BF50 oil filter
- All Honda maintenance guides
- Free Honda boat valuation
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