Mercury 4-Stroke Engine Oil – 10W-30, 4L | Part 8M0078638

Mercury 4-Stroke Engine Oil – 10W-30 | 4 Litres

About This Oil

This is the OEM-specified SAE 10W-30 4-stroke crankcase oil for Mercury FourStroke outboards and MerCruiser sterndrive engines, sold in a 4-litre container. The same marine-specific formula as the 1L version (8M0078637), the 4L size is ideal for full oil changes on larger-displacement engines, twin-engine boats, or stocking up for a full season. NMMA FC-W and FC-W Catalyst Compatible certified.

Compatible Applications

• Mercury FourStroke outboards 2.5 HP – 150 HP requiring 10W-30 crankcase oil
• Mercury 75 HP – 150 HP EFI FourStroke outboards
• Mercury Pro XS FourStroke models
• Mercury 3.4L V6 FourStroke outboards
• MerCruiser 3.0L, 4.3L V6, 5.0L V8, 5.7L V8, and 6.2L V8 sterndrive engines
• Other 4-stroke marine engines specifying SAE 10W-30 marine-rated oil
• Always verify the recommended viscosity in your engine owner’s manual and against your serial number range before ordering

Service Interval

Change engine oil and filter every 100 hours or annually, whichever comes first — per the Mercury and MerCruiser service manual. Always replace the oil filter at each oil change. Do not extend intervals in saltwater or high-hour applications. Most Mercury 4-stroke outboards require 1.5–2.5 litres per change; MerCruiser sterndrives typically require 4–5 litres — confirm your engine’s capacity in the service manual.

Technical FAQ

Q: How does the 4L differ from the 1L (8M0078637)?
A: Same oil, larger container. The 4L is more economical per litre and covers most full oil changes in a single bottle. The 1L (8M0078637) is better for top-ups or small-displacement engines.

Q: Can I use automotive 10W-30 instead?
A: Not recommended. Automotive oils lack the corrosion inhibitors and shear-stability additives required for marine environments. Using non-marine oil can void warranty coverage and accelerate internal wear.

Q: My engine calls for 25W-40 — can I use this 10W-30?
A: No. Always use the viscosity specified in your engine’s service manual. If your engine requires 25W-40, see our Mercury 4-Stroke Marine Engine Oil – 25W-40, 1L (8M0078639) or Mercury 4-Stroke Marine Engine Oil – 25W-40, 4L (8M0078640).

Q: Is this the same as the synthetic blend 10W-30?
A: No. This is a conventional (mineral-base) marine oil. For a synthetic blend in 10W-30, see Mercury Synthetic Blend 10W-30, 1 Gallon (8M0149213).

Related Parts

• Mercury 4-Stroke Engine Oil – 10W-30, 1L (8M0078637) — smaller size for top-ups or compact engines
• Mercury 4-Stroke Marine Engine Oil – 25W-40, 1L (8M0078639)
• Mercury 4-Stroke Marine Engine Oil – 25W-40, 4L (8M0078640)
• Mercury Quicksilver Oil Filter 877761K01 – 75–150 HP FourStroke
• Mercury MerCruiser Quicksilver Oil Filter 822626Q15
• Mercury Oil Change Kit – 15 & 20 HP Carbureted FourStroke (8M0081914)
• Mercury MerCruiser Oil Change Kit – V6/V8 10W-30 (8M0187621)
• Browse all Mercury MerCruiser Engine Maintenance Parts

Parts Desk Insights

Best use case: Full scheduled oil changes on Mercury 4-stroke outboards and MerCruiser sterndrives that specify 10W-30. The 4L size is the right choice for most complete oil changes — particularly MerCruiser sterndrives and larger-displacement outboards — and offers better value per litre than buying multiple 1L bottles. Also a smart buy for twin-engine boats or anyone servicing multiple engines in a season.

Common mistakes: Customers sometimes order the 4L when they only need a top-up and would be better served by the 1L (8M0078637). The most frequent error is ordering 10W-30 when the engine actually requires 25W-40 — always check the owner’s manual viscosity spec first. Always replace the oil filter at the same time; ordering oil without a filter is a common oversight. Do not confuse this conventional oil with the synthetic blend versions (8M0149213).