What the F6RTC cross reference tells you

The F6RTC is a Champion spark plug with a specific heat range and electrode design. When you cross-reference it, you are looking for spark plugs from other manufacturers — Bosch, NGK, Autolite, Denso — that have the same heat range, gap, and thread size so they will work in the same engine. The cross reference does not mean the plugs are identical, only that they perform the same job in your vehicle.

Cross-referencing matters because Champion plugs are not always in stock at every parts store, or you may want to compare prices across brands. A proper cross reference ensures you do not buy a plug that is too hot, too cold, or the wrong size for your engine's needs.

The F6RTC itself is a hot plug — it has a longer insulator nose that retains heat — and it carries a standard 0.030-inch gap. It threads into engines that call for a 14mm plug with a reach of 3/8 inch. These specifications are what you match when you cross-reference.

Key Takeaways

  • The F6RTC is a Champion hot-range plug with a 14mm thread, 3/8-inch reach, and 0.030-inch gap that works in older small engines and some lawn equipment.
  • NGK equivalent is typically the BPM6F; Bosch equivalent is typically the WS8F; Autolite equivalent is typically the 206.
  • Cross-reference charts vary slightly between manufacturers, so confirm the heat range and reach match before you buy.
  • You can verify a cross reference by checking the plug's part number against the manufacturer's official spec sheet or by calling the parts store with both the original plug number and the replacement brand.

Common cross-reference matches for the F6RTC

The most widely recognized cross-reference matches are NGK BPM6F, Bosch WS8F, and Autolite 206. These three plugs share the same heat range, thread size, and reach as the F6RTC. However, the exact match can vary depending on the engine process and the year the plug was manufactured, so these are starting points rather than guarantees.

NGK plugs are sold in most auto parts stores and online retailers. The BPM6F is their direct hot-range equivalent and will fit the same socket and gap setting. Bosch plugs are also widely available; the WS8F is their comparable hot plug. Autolite 206 is less common in modern inventory but still obtainable through specialty suppliers or online.

If you cannot find an exact match, do not assume a different number will work. A plug that looks similar but has a different heat range or reach can cause fouling, poor starting, or engine damage. Always verify before you install.

How to use a cross-reference chart

Cross-reference charts are published by spark plug manufacturers, parts retailers, and equipment manuals. You start with the F6RTC and look across the row to find the equivalent from another brand. The chart will show the part number, heat range, gap, and thread size side by side.

The most reliable charts come directly from the manufacturer — Champion, NGK, Bosch, and Denso all publish them online or in printed form. Parts retailers like AutoZone, O'Reilly, and NAPA also maintain cross-reference databases that you can search by plugging in the F6RTC number. Many of these databases are free and searchable on their websites.

When you use a chart, read across the entire row, not just the part number. Confirm that the heat range, gap, and reach all match. If one specification differs, that plug may not be a true cross reference for your process.

Why heat range and reach matter in a cross reference

The heat range of a spark plug determines how quickly it sheds heat into the engine. A hot plug (like the F6RTC) has a longer insulator nose and stays hotter, which helps prevent fouling in engines that run cool or at low speeds. A cold plug sheds heat faster and is used in high-performance or high-temperature engines.

If you install a cold plug where a hot plug is needed, the plug will foul — carbon and oil will build up on the electrodes and the engine will misfire or fail to start. If you install a hot plug where a cold plug is needed, the plug can overheat and cause preignition, which damages the engine. The F6RTC is a hot plug, so its cross-reference replacements must also be hot plugs.

The reach is the length of the threaded portion. The F6RTC has a 3/8-inch reach. If you install a plug with a longer reach, it will protrude too far into the combustion chamber and can be struck by the piston. A shorter reach will not seat properly and will leak compression. Always match the reach exactly.

Where to find official cross-reference information

The most authoritative source is the engine or equipment manufacturer's manual. If you are replacing a spark plug in a lawn mower, generator, or small engine, the manual will list the correct plug and often include cross-reference information for other brands.

Champion's official website has a cross-reference tool where you can enter the F6RTC and see equivalent plugs from other manufacturers. NGK, Bosch, Denso, and Autolite all maintain similar tools. These are free to use and updated regularly.

Parts retailers maintain searchable databases. You can visit AutoZone.com, OReillyAuto.com, or NAPA.com, enter the F6RTC in the search box, and the site will show you compatible plugs from multiple brands along with pricing and availability at your local store. This approach also lets you compare prices before you buy.

What to do if you cannot find an exact cross reference

If the F6RTC is not available and you cannot find a direct cross reference, contact the equipment manufacturer or a dealer who specializes in that brand. They can tell you which plugs are approved for your specific engine and may have stock of the original or a verified alternative.

You can also call a local parts store and give them both the F6RTC number and the brand you want to switch to. The store's computer system can cross-reference it and tell you whether a match exists. If the store says there is no match, ask them to check the heat range and reach specifications — sometimes a plug with a slightly different part number will still work if the specs align.

Do not guess or install a plug based on appearance alone. A wrong plug can cause starting problems, poor fuel economy, or engine damage that costs far more than the price of the correct spark plug.

Frequently Asked Questions

Can I use an NGK BPM6F in place of an F6RTC?

Yes, the NGK BPM6F is the standard cross-reference equivalent for the F6RTC. It has the same heat range, 14mm thread, 3/8-inch reach, and 0.030-inch gap. Confirm these specs match your engine's requirements before you install.

What does the "F" in F6RTC mean?

The "F" indicates the heat range — in Champion's system, F is a hot plug. The "6" refers to the thread size and reach, and "RTC" is the resistor type and design code. When you cross-reference, you need to match that heat range letter to may support the replacement plug performs the same way.

Is there a difference between an F6RTC and an F6RTC-2?

The "-2" suffix usually indicates a newer version or a slight design change, but both should have the same heat range, thread, and reach. Check the spec sheet to confirm they are interchangeable for your engine before you buy the newer version.

Where can I find the cross reference if my parts store does not have it?

Champion's website, NGK's website, and Bosch's website all have free cross-reference tools. You can also check the equipment manual or contact the engine manufacturer directly. Most parts stores can also look it up in their computer system if you call with the F6RTC number.

Do I need to change the gap if I use a cross-reference plug?

A proper cross-reference plug comes pre-gapped to the correct setting, usually 0.030 inches for the F6RTC. Do not adjust the gap unless the plug manufacturer's spec sheet says it differs from the original. Changing the gap on a new plug can damage the electrodes.