The 18‑7875 is typically specified for Onan EF series engines and similar models. It has a thread size of approximately 3/4‑16, an outer diameter of roughly 97 mm (3.82 in), and a height of about 131 mm (5.16 in). Cross-referencing ensures proper fitment, seal integrity, and filtration performance, avoiding engine damage or oil leaks.
Onan 18‑7875 Oil Filter Cross Reference
| Brand / Manufacturer | Part Number(s) | Notes / Common Applications |
|---|---|---|
| Sierra | 18‑7875 / 18‑7875‑1 | Original marine filter |
| FRAM | PH8A | Classic automotive/marine equivalent |
| Luber-Finer | PH8A | Heavy-duty version |
| WIX | 51452 / 51515 | Common marine listing |
| Baldwin | B2 | Standard spin-on |
| NAPA Gold | 1515 | Widely available |
| AC Delco | PF2 | Original GM/Ford equivalent |
| Motorcraft | FL‑1A / FL‑1HP | Ford OEM, common cross-reference |
| Purolator | L30001 | Premium version |
| Mobil 1 | M1‑301 | Extended performance |
| K&N | HP‑3001 | High-flow performance |
| Hastings | LF240 | Standard |
| Mallory | 9‑57802 | Marine applications |
| Crusader | 22679 | OEM for Crusader engines |
| Pleasurecraft (PCM) | R077001 | OEM for PCM marine engines |
| Mercury / Quicksilver | 35‑802886Q / 35‑8M0116378 | Primary OEM replacement |
| Mercury (older) | 35‑60565 / 56874 | Older Mercury part numbers |
| OMC | 502900 | OMC/Volvo marine engines |
| Volvo Penta | 835779 | Volvo marine equivalent |
| Luber-Finer | LFP10016 | Industrial-grade full-flow |
| Donaldson | P550345 | Industrial and heavy-duty marine |
| Baldwin | B4505 | Industrial and generator use |
| Napa | 265‑1875 | Aftermarket compatible for Onan EF series |
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Best Filter Option for Onan 18‑7875
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1. Sierra 18‑7875 / 18‑7875‑1
Features:
- Direct reference for Onan-compatible engines.
- Full-flow spin-on design with 3/4‑16 thread size.
- Durable steel housing with high-quality filter media.
- The “‑1” variant has similar dimensions, suitable for applications requiring slight variations.
2. FRAM PH8A
Features:
- Frequently cross-referenced as compatible with Sierra 18‑7875.
- Thread size 3/4‑16, matching Sierra specifications.
- Reliable aftermarket brand with broad availability.
- Suitable for Onan EF series and similar generators.
3. WIX 51515
Features:
- Recognized aftermarket alternative with compatible thread and dimensions.
- High dirt-holding capacity with performance-grade filter media.
- Practical substitute when OEM filters are unavailable.
- Ideal for Onan generator maintenance where 18‑7875 filters are used.
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Onan Applications
For Onan engines, the 18‑7875 (or its equivalents) is mainly used in:
- Onan EF series generators
- Industrial diesel or gasoline Onan engines in backup power systems
- Marine Onan engines in small boats or yachts
For other Onan models, variations such as 18‑7878‑1 may be required depending on clearance and filter height. Always verify dimensions and specifications before replacement.
Maintenance Tips
- Check Clearance: Ensure the filter will not interfere with nearby components. Some models may require shorter or alternative filters.
- Gasket Preparation: Apply a thin film of clean engine oil to the new gasket to ensure proper sealing and easier removal later.
- Pre-Fill (if allowed): Pre-filling the filter with oil can reduce dry-start risk.
- Torque Properly: Follow manufacturer torque specifications to avoid leaks or damage.
- Oil Change Intervals: Even with a correct filter, adhere to the recommended oil change schedule to maintain engine life.
- Double-Check Cross-Reference: Confirm thread size, height, and diameter match your engine’s requirements before installation.
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FAQs
What is the difference between Sierra 18‑7875 and 18‑7875‑1?
The Sierra 18‑7875 and 18‑7875‑1 are very similar spin-on oil filters, often interchangeable for the same Onan engine models. The main difference usually lies in minor manufacturing updates such as gasket material, pressure bypass rating, or part numbering for inventory purposes. Physically, dimensions like thread size, outer diameter, and height are typically the same, so either can work as a replacement, but it’s always best to confirm fitment for your specific engine.
What is the cross reference for 18‑7897 oil filter?
The 18‑7897 oil filter is another Sierra filter commonly used in Onan generators and similar engines. Known equivalents include:
- FRAM PH3614
- WIX 51516
- Baldwin B4507
- Donaldson P550347
- These alternatives maintain the same thread size, filtration rating, and height to ensure compatibility with engines listed for 18‑7897.
What oil filter does an Onan 4000 generator use?
Onan 4000 generators typically use the Sierra 18‑7875 oil filter or its equivalents, such as FRAM PH8A, Mallory 9‑57802, or Baldwin B4505. Always check the engine model and filter clearance before installation to ensure proper fit and reliable oil filtration.
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What is the cross reference for 18‑7902 oil filter?
The Sierra 18‑7902 oil filter is compatible with certain Onan and industrial engine models. Common cross-reference options include:
- FRAM PH8A or PH3614 (depending on engine series)
- Baldwin B4508
- WIX 51517
- Donaldson P550348
- These alternatives are designed to match the threading, height, and filtration specifications of the 18‑7902 filter.
What happens if you put the wrong oil filter on a lawn mower?
Using the wrong oil filter can lead to several issues:
- Oil leaks if the gasket does not seal properly.
- Oil starvation if the filter’s flow rate or bypass valve is incompatible, potentially damaging the engine.
- Reduced filtration efficiency, allowing dirt and debris to circulate in the engine.
- Physical interference if the filter is too long or wide for the engine compartment.
- Always use the correct filter specified for your mower or a verified cross-reference equivalent.
How to tell if an oil filter is compatible?
To determine if an oil filter is compatible:
- Check thread size and type, it must match the engine’s filter mount.
- Verify height and outer diameter, ensure there is enough clearance in the engine bay.
- Confirm bypass valve rating, which prevents oil starvation if the filter becomes clogged.
- Check filtration rating, the micron rating should meet or exceed the original filter’s specification.
- Review manufacturer cross-reference lists, these provide verified equivalents for your engine.
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Final words
The Onan 18‑7875 oil filter is a reliable and widely used option for many Onan generators and engines. Its cross-references, including FRAM PH8A, Mallory 9‑57802, Baldwin B4505, and others, make it easier to source replacements while ensuring proper filtration. Always verify the specific engine application and physical dimensions when selecting a replacement to maintain optimal performance and engine longevity.
