Sierra 9420CAT3 4-Stroke Mineral Marine Outboard Engine Oil, 10W-30, 1 Gallon
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Sierra 9420CAT3 4-Stroke Mineral Marine Engine Oil, 10W-30 – 1 Gallon
A premium mineral-base 10W-30 engine oil formulated specifically for marine 4-stroke outboard engines. Sierra 9420CAT3 meets or exceeds the lubrication requirements of Mercury, Yamaha, Johnson-Evinrude, Suzuki, and Honda outboards — delivering reliable protection across a wide range of engine brands and operating conditions.
The 1-gallon jug is the practical middle ground: enough for multiple oil changes on smaller engines, or a full service plus top-up reserve on larger outboards, without the commitment of drum-quantity purchasing.
Key Features
- Marine-specific formulation — engineered for the demands of 4-stroke outboard engines, not repurposed automotive oil
- Anti-wear additives — reduce friction and protect engine internals under sustained load
- Maximum corrosion protection — guards against moisture and salt exposure in the marine environment
- Sludge control — keeps engine internals cleaner for better long-term efficiency
- Low-temperature viscosity — supports reliable cold-weather and cold-start performance
- Broad OEM compatibility — meets API SJ, CF-2, and CH-4 service classifications
Specifications
- Viscosity: SAE 10W-30
- Base stock: Mineral
- API service: SJ, CF-2, CH-4
- Volume: 1 US gallon (3.78 L)
- Part number: 9420CAT3 | SKU: 47-9420CAT3
- Compatible engines: Mercury, Yamaha, Johnson-Evinrude, Suzuki, Honda 4-stroke outboards
Best Use Case
The 1-gallon format is the right choice for recreational boaters and small marina shops who service one or two 4-stroke outboards regularly and want a cost-effective, reliable mineral oil without the volume commitment of a drum. It’s particularly well-suited for mid-size outboards (50–150 HP) where a gallon covers a full drain-and-fill with oil to spare.
Also available in a 1-Quart size (9420CAT2) for smaller engines or top-ups, and in a 55-Gallon Drum (9420CAT7) for high-volume shop use. For a synthetic blend upgrade with FC-W certification and extended drain interval performance, see the Sierra 9421CAT2 Synthetic Blend 10W-30.
Parts Desk Insights
Best use case is the recreational single-engine boater or small shop doing seasonal oil changes on 4-stroke outboards. The gallon is the most popular format for DIY customers — it’s the right size for one full service on most mid-size outboards with a small reserve. Upsell path: customers doing multiple engines or buying frequently should be directed to the 55-gallon drum (9420CAT7) for better cost-per-litre value. Always flag the FC-W certification question for Yamaha and Mercury customers — if they’re warranty-conscious, redirect to the Sierra 9421CAT2 Synthetic Blend (FC-W). Confirm OEM oil spec in the owner’s manual before recommending.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.