When your Honda GCV160 engine starts burning oil, it’s not just a performance issue—it’s a signal that something deeper is happening under the hood. This small but mighty engine powers everything from lawn mowers and pressure washers to generators and water pumps, and when it begins consuming oil at an abnormal rate, it can quickly escalate into costly repairs or even premature engine failure. One of the first components mechanics and DIYers check is the spark plug. While a worn or fouled spark plug isn’t always the root cause of oil burning, it’s often a contributing factor—or at the very least, a symptom of underlying problems like worn piston rings, valve guide seals, or cylinder wall damage. Replacing the spark plug with the right one can restore ignition efficiency, improve combustion stability, reduce emissions, and in some cases, even slow the rate of oil consumption by ensuring complete fuel burn.
This comprehensive buying guide is designed for homeowners, landscapers, small engine technicians, and DIY enthusiasts who rely on their GCV160-powered equipment and want to make an informed decision when selecting a replacement spark plug. Whether you’re troubleshooting persistent misfires, black smoke from the exhaust, or simply performing routine maintenance, choosing the correct spark plug is critical. The market is flooded with options—from OEM Honda plugs to aftermarket brands like NGK, Denso, Champion, and Autolite—each claiming superior performance. But not all spark plugs are created equal, especially when dealing with an engine that’s already under stress from oil burning. In this guide, you’ll learn how to identify the best spark plug for your specific situation, understand the technical specifications that matter most, avoid common pitfalls, and ultimately extend the life of your GCV160 engine without breaking the bank.
We’ll walk you through key factors like heat range, electrode material, gap specifications, and compatibility, while also addressing how oil fouling impacts plug performance. You’ll discover the differences between standard copper, platinum, and iridium plugs, and why one might be better suited for a compromised engine than another. We’ll compare top brands, break down pricing tiers, highlight expert tips for installation and maintenance, and answer frequently asked questions based on real-world experience. By the end of this guide, you won’t just know which spark plug to buy—you’ll understand why it’s the right choice for your GCV160, especially in the context of oil consumption issues.
What to Look for When Buying Buying Guide
1. Heat Range Compatibility
The heat range of a spark plug determines how well it dissipates heat from the combustion chamber. In a GCV160 engine that’s burning oil, excess oil droplets can coat the spark plug insulator, lowering its operating temperature and increasing the risk of fouling. A plug with too cold a heat range won’t burn off carbon and oil deposits, leading to misfires and hard starts. Conversely, a plug that’s too hot can cause pre-ignition or detonation, especially if the engine is already running rich due to oil contamination. For the GCV160, Honda specifies a heat range equivalent to NGK’s CR5HSA or CR6HSA (depending on model year and application). If your engine is burning oil, opting for a slightly colder plug (like the CR6HSA) can help prevent overheating and reduce the chance of oil-induced fouling. Always cross-reference your owner’s manual or consult a Honda parts diagram to confirm the correct heat range.
2. Electrode Material and Design
Spark plug electrodes come in various materials, each with distinct advantages. Standard copper-core plugs (like the NGK CR5HSA) offer excellent conductivity and are affordable, making them a popular OEM choice. However, they wear out faster—typically every 10,000 to 15,000 miles—and are more prone to erosion in engines with oil contamination. Platinum plugs last longer and resist fouling better, while iridium plugs (such as the Denso IK06 or NGK ICR6HSA) feature a fine-wire center electrode that requires less voltage to fire, improving ignition reliability in compromised engines. For a GCV160 burning oil, iridium or double-platinum plugs are often the best choice because they maintain a strong spark even when coated with oil residue. The finer electrode also reduces the likelihood of misfires during cold starts or under load.
3. Proper Gap Specification
The spark plug gap—the distance between the center and ground electrode—directly affects ignition performance. Honda specifies a gap of 0.024 to 0.028 inches (0.6 to 0.7 mm) for the GCV160. However, in engines burning oil, carbon and oil deposits can alter the effective gap over time. A plug that’s gapped too wide may not fire consistently if the ignition system is weakened by age or oil contamination. Conversely, a gap that’s too narrow produces a weaker spark, leading to incomplete combustion and increased emissions. Always check and adjust the gap before installation using a wire-type gap tool. Pre-gapped plugs from reputable brands are convenient, but it’s wise to verify the gap anyway, as shipping and handling can alter it. For oil-burning engines, a slightly narrower gap (0.026 inches) can improve reliability.
4. Resistance to Fouling
Oil fouling occurs when engine oil seeps past worn piston rings or valve seals and coats the spark plug. This creates a conductive layer that shorts the spark, causing misfires, rough idling, and black smoke. In severe cases, the plug becomes completely carbonized and must be replaced. To combat this, look for spark plugs with anti-fouling features such as a projected nose design (which positions the electrode further into the combustion chamber for better exposure to the air-fuel mixture) or a V-groove ground electrode (found in some NGK plugs) that enhances flame kernel development. Iridium and platinum plugs also resist fouling better than copper due to their superior durability and lower operating temperatures. Additionally, some high-performance plugs include a built-in resistor to reduce electromagnetic interference, which can help stabilize ignition in older ignition systems.
5. Brand Reputation and OEM Compatibility
Not all spark plugs are created equal, and brand matters—especially for small engines like the GCV160. Honda originally equips these engines with NGK CR5HSA or CR6HSA plugs, and sticking with NGK ensures compatibility and reliable performance. Other reputable brands include Denso (known for precision engineering), Champion (a trusted name in small engines), and Autolite (offering solid value). Avoid generic or unbranded plugs sold in bulk packs, as they often use inferior materials and inconsistent manufacturing processes. These cheap plugs may fit, but they can fail prematurely, cause misfires, or even damage the ignition coil. When in doubt, choose a plug that matches the OEM specification exactly. Cross-referencing part numbers (e.g., NGK CR6HSA = Denso W16EX-U) ensures you’re getting a true equivalent.
6. Warranty and Support
While spark plugs are consumable parts, reputable manufacturers often back their products with warranties against defects in materials and workmanship. NGK, for example, offers a limited warranty on its automotive and small engine plugs, and Denso provides similar coverage. This may not cover wear from normal use or oil fouling, but it does protect against manufacturing flaws like cracked insulators or faulty electrodes. When buying online or from third-party sellers, ensure the product is new and sealed in original packaging. Counterfeit plugs are a growing problem, especially on marketplaces like Amazon and eBay. Look for authorized dealers or retailers with strong return policies. If a plug fails prematurely due to a defect, you’ll want the option to exchange or refund it.
7. Ease of Installation and Accessibility
The GCV160 has a relatively accessible spark plug location, but tight engine compartments (especially on lawn mowers) can make replacement tricky. A spark plug with a standard 13/16-inch (21mm) hex size and 3/4-inch (19mm) reach (thread length) will fit most GCV160 models. However, some aftermarket plugs may have slightly different dimensions, so always double-check compatibility. A plug with a gasket seat (as opposed to a tapered seat) ensures a proper seal and prevents compression leaks. Using a quality spark plug socket with a rubber insert helps prevent cracking the ceramic insulator during installation. Torque to Honda’s specification (typically 13–16 ft-lbs) to avoid over-tightening, which can strip threads or damage the cylinder head.
8. User Reviews and Real-World Performance
While specifications matter, real-world feedback from other GCV160 owners is invaluable. Look for reviews that specifically mention oil burning, fouling, or extended use in lawn mowers or pressure washers. Plugs that perform well in clean, well-maintained engines may fail quickly in oil-burning applications. Pay attention to comments about cold starts, idle stability, and fuel efficiency. For example, many users report that switching from a standard copper plug to an iridium Denso IK06 resolved persistent misfires in older GCV160 engines with known oil consumption issues. However, avoid reviews that lack detail—generic praise like “works great” without context isn’t helpful. Focus on verified purchases and long-term users who’ve tested the plug over hundreds of operating hours.
Different Types of Buying Guide
Common Buying Mistakes to Avoid
❌ Mistake: Choosing the Wrong Heat Range
Why it’s bad: Using a plug that’s too hot can cause pre-ignition, especially in an engine already stressed by oil burning. A plug that’s too cold won’t burn off oil and carbon deposits, leading to fouling and misfires. Both scenarios reduce engine efficiency and can accelerate wear.
What to do instead: Always match the OEM-specified heat range. For most GCV160 models, that’s NGK CR5HSA (standard) or CR6HSA (colder). If your engine burns oil, the CR6HSA is often the safer choice to prevent overheating.
❌ Mistake: Ignoring the Spark Plug Gap
Why it’s bad: A misgapped plug can cause weak sparks, hard starts, or complete misfires. Pre-gapped plugs can shift during shipping, and oil-fouled engines may require a slightly narrower gap for reliable ignition.
What to do instead: Always measure the gap with a wire feeler gauge before installation. Adjust to 0.026–0.028 inches, and recheck after a few hours of operation if fouling is suspected.
❌ Mistake: Buying Cheap, Unbranded Plugs
Why it’s bad: Generic plugs often use low-quality materials, inconsistent manufacturing, and incorrect heat ranges. They may fit, but they fail quickly, cause ignition problems, and can even damage the ignition coil.
What to do instead: Stick with reputable brands like NGK, Denso, or Champion. Verify part numbers and buy from authorized dealers to avoid counterfeits.
❌ Mistake: Overlooking Electrode Material
Why it’s bad: Copper plugs wear out fast in oil-burning engines. Platinum and iridium last longer and resist fouling better, making them more cost-effective over time despite the higher upfront price.
What to do instead: For engines with known oil consumption, upgrade to iridium or double-platinum plugs. The improved spark reliability and longevity justify the extra cost.
❌ Mistake: Reusing Old Wires or Boots
Why it’s bad: Worn ignition wires or cracked boots can cause arcing, reducing spark energy. This is especially problematic in oil-fouled engines where spark demand is already high.
What to do instead: Inspect the spark plug wire and boot during replacement. Replace if cracked, brittle, or showing signs of carbon tracking.
❌ Mistake: Not Addressing the Root Cause of Oil Burning
Why it’s bad: A new spark plug won’t fix worn piston rings, valve seals, or cylinder wear. Continuing to operate the engine without addressing these issues will lead to repeated fouling and eventual engine failure.
What to do instead: Use a compression tester to check cylinder health. If compression is low or varies significantly between tests, consider a top-end rebuild or professional diagnosis.
❌ Mistake: Installing Without Anti-Seize or Dielectric Grease
Why it’s bad: Thread galling or seized plugs can occur, especially in aluminum cylinder heads. Lack of dielectric grease on the boot can lead to moisture intrusion and arcing.
What to do instead: Apply a small amount of anti-seize to the threads (sparingly—too much can alter torque specs) and dielectric grease to the inside of the boot to ensure a secure, moisture-resistant connection.
Budget Guidelines: How Much Should You Spend?
Entry-Level ($3–$6): This tier includes standard copper-core plugs like the NGK CR5HSA or Champion RJ19LM. These are ideal for low-hour engines with minimal oil consumption and are perfect for routine maintenance. Expect a service life of 10,000–15,000 miles. While affordable, they wear faster and are more prone to fouling in compromised engines. Best for users who replace plugs annually and prioritize cost over longevity.
Mid-Range ($6–$10): This is the sweet spot for most GCV160 owners. Platinum plugs like the Denso PK20PR-P8 or NGK PFR6H offer better durability, improved fouling resistance, and longer service intervals (up to 30,000 miles). They’re a smart upgrade for engines with mild oil burning or frequent use. The slight price increase is justified by reduced maintenance and improved reliability.
Premium ($10–$15): Iridium plugs such as the Denso IK06 or NGK ICR6HSA fall into this category. Designed for high-performance and long-life applications, they feature fine-wire electrodes that require less voltage to fire, making them ideal for oil-burning engines with weakened ignition systems. With lifespans exceeding 60,000 miles, they offer the best value for high-hour users and those seeking maximum reliability.
Luxury ($15+): Racing or specialty plugs like the NGK R7437-10 (a 10mm thread racing plug) or multi-electrode designs are overkill for most GCV160 applications. These are best reserved for modified engines or extreme conditions. For standard use, the performance gains don’t justify the cost.
Expert Tips for Getting the Best Deal
– Buy in Bulk for Multiple Units: If you own several GCV160-powered tools (e.g., mower, generator, pressure washer), buying a 3- or 6-pack of iridium plugs can save 15–20% compared to individual purchases. Just ensure they’re stored in a dry, temperature-controlled environment.
– Shop During Off-Season: Spark plug prices often drop in late fall and winter when lawn care demand is low. Retailers like Home Depot, Lowe’s, and Northern Tool frequently run promotions on small engine parts during these months.
– Use Manufacturer Rebates: NGK and Denso occasionally offer mail-in rebates on multi-packs. Check their websites or packaging for current promotions—these can reduce the effective price by $2–$5 per plug.
– Compare Online vs. In-Store: Online retailers like Amazon, eBay, and SparkPlugCrossReference.com often have lower prices and wider selection. However, verify seller ratings and return policies. In-store purchases allow immediate inspection but may carry a markup.
– Check for OEM Overstock: Some Honda dealers sell genuine NGK plugs at discounted rates when clearing old inventory. These are identical to new OEM parts but may lack retail packaging.
– Test Before Committing: If possible, install one premium plug (e.g., Denso IK06) and run the engine for 10–15 hours. Monitor for improvements in start-up, idle, and smoke output. If performance improves, replace the rest.
– Read the Fine Print on Warranties: Most spark plug warranties don’t cover wear from oil fouling or improper installation. However, they do protect against defects. Keep your receipt and packaging in case of early failure.
– Combine with Other Maintenance: Replace the air filter and fuel filter at the same time. A clean air filter reduces oil contamination from blow-by, and a fresh fuel filter ensures proper fuel delivery, both of which support spark plug performance.
Frequently Asked Questions
Q: Can a bad spark plug cause my GCV160 to burn oil?
A: Not directly. Oil burning is typically caused by worn piston rings, valve guide seals, or cylinder wear. However, a fouled or misfiring spark plug can lead to incomplete combustion, which increases carbon buildup and may exacerbate oil consumption over time. Replacing the plug improves combustion efficiency but won’t fix the root mechanical issue.
Q: How often should I replace the spark plug in a GCV160 that burns oil?
A: In normal conditions, every 100 hours of operation or annually. For engines burning oil, inspect the plug every 25–50 hours. If you see heavy carbon or oil fouling, replace it immediately. Iridium plugs can extend this interval, but frequent inspection is still recommended.
Q: Is it safe to use a colder spark plug in my oil-burning GCV160?
A: Yes, and it’s often recommended. A colder plug (like the NGK CR6HSA instead of CR5HSA) dissipates heat more effectively, reducing the risk of pre-ignition and helping burn off oil deposits. Just ensure it’s within Honda’s specified range.
Q: Can I clean and reuse a fouled spark plug?
A: You can try cleaning with a wire brush or spark plug cleaner, but this is a temporary fix. Oil-fouled plugs often have internal damage or eroded electrodes. For reliability, replacement is strongly advised.
Q: Will upgrading to iridium improve fuel economy?
A: Possibly. A stronger, more consistent spark ensures complete combustion, which can improve fuel efficiency by 1–3% in compromised engines. The savings are modest but add up over time, especially with frequent use.
Q: What’s the difference between NGK CR5HSA and CR6HSA?
A: The CR6HSA is one heat range colder than the CR5HSA. Both fit the GCV160, but the CR6HSA is better for high-load or oil-burning applications. The CR5HSA is standard for most models.
Q: Can I use a automotive spark plug in my GCV160?
A: Only if it matches the exact specifications (thread size, reach, heat range, gap). Most automotive plugs are incompatible. Stick to small engine-specific plugs designed for lawn equipment.
Q: Why does my new spark plug keep fouling?
A: Persistent fouling indicates an underlying mechanical issue—likely worn piston rings or valve seals. A compression test can confirm. Continuing to replace plugs without addressing the root cause will lead to repeated failures.
Q: Should I replace the spark plug wire too?
A: Not always, but inspect it. If the wire is cracked, brittle, or shows carbon tracking (black lines), replace it. A weak ignition system can’t deliver full voltage, especially to premium plugs.
Q: Can I use dielectric grease on the spark plug threads?
A: No—use anti-seize sparingly on the threads. Dielectric grease is only for the inside of the boot to prevent moisture intrusion and arcing.
Our Final Recommendations
– Best for Budget-Conscious Buyers: NGK CR5HSA – The OEM-standard copper plug. Affordable, reliable, and easy to find. Ideal for low-hour engines with minimal oil issues.
– Best Overall Value: Denso IK06 (Iridium) – Offers superior spark performance, excellent fouling resistance, and long life. Perfect for GCV160 engines with mild to moderate oil burning.
– Best Premium Option: NGK ICR6HSA (Iridium) – A colder heat range iridium plug designed for high-stress applications. Ideal for engines with confirmed oil consumption or frequent heavy use.
– Best for Beginners: Champion RJ19LM – Simple, affordable, and widely available. Easy to gap and install, making it a great choice for first-time DIYers.
– Best for Advanced Users: Denso PK20PR-P8 (Platinum) – Offers a balance of performance and durability. Great for users who want to upgrade from copper without the cost of iridium.
Conclusion: Making the Right Choice
Choosing the right spark plug for your GCV160 engine—especially one that’s burning oil—is about more than just fitting a part. It’s about understanding how ignition, combustion, and engine wear interact, and selecting a component that supports reliable performance under stress. While a new spark plug won’t solve mechanical issues like worn rings or valve seals, it can significantly improve ignition efficiency, reduce misfires, and help you get the most out of your engine’s remaining life.
Throughout this guide, we’ve emphasized the importance of heat range, electrode material, proper gapping, and brand reliability. We’ve compared plug types, highlighted common mistakes, and provided actionable tips to help you make a confident, informed decision. Whether you’re a weekend warrior maintaining a single mower or a professional managing a fleet of equipment, the right spark plug can mean the difference between a smooth-running engine and constant frustration.
Remember: when dealing with oil burning, the spark plug is just one piece of the puzzle. Use this guide to choose the best plug for your situation, but also consider a full engine evaluation if problems persist. Prioritize quality over cost, invest in iridium for long-term reliability, and never skip routine inspections. Your GCV160 deserves the best—and so do you. Take action today, replace that plug with confidence, and keep your equipment running strong for seasons to come.