Bosch R10 To NGK: Compatibility For Swapping

Bosch and NGK are famous for making quality and durable spark plugs. Are you planning to switch the Bosch R10 series of spark plugs with an NGK one? Well, you cannot simply swap a Bosch spark plug with any NGK one.

There are many important factors, such as tread length, thread diameter, electrode gap length, core material, and heat rating, to be considered before doing so. It can be tedious to manually search for compatible NGK spark plugs by reading and matching the part numbers.

In this article, we have brought you a compatibility chart using which you can easily determine any Bosch R10 to NGK in no time. Hence stay tuned and go through the article till the end.

Bosch R10 To NGK Cross Reference Chart

The standard construction process and structure for all the sparkplugs are quite identical. But there are many minute differences between them, due to which you cannot directly perform swapping.

You might have noticed an “R10” written in the part number of Bosch sparkplugs used in small trimmers. It specifies certain features of the Bosch sparkplugs.

The “R” stands for the resistor construction, whereas ten means the heat rating of the sparkplug. Moreover, ten is the highest number on the scale, which determines the heat rating. It shows the sparkplug is a cold-featured one.

Therefore to get an NGK sparkplug for swapping a Bosch sparkplug, you must get a similar resistor and heat rating for optimum compatibility.

You can use the following cross-reference chart to ensure which NGK spark plug models are Bosch R10 spark plug compatible.

Bosch R10 SeriesCompatible NGK Sparkplugs

How To Read Sparkplug Part Number?

The numbers mentioned on the packaging of the sparkplugs do not only show the model or batch number. It has other significance as well. The combination of alphanumeric code includes the structural and functional specifications of the spark plug.

However, the meaning of the code is different for different brands, but the core structure is the same for all. For better understanding, referring to the manufacturer’s specifications and manual is recommended.

Thread Diameter And Socket Type

The first letter or first two letters specify the sparkplugs’ thread diameter and socket type. Most sparkplugs, including Bosch and NGK, use a standard 14mm thread and 19mm socket. Some sparkplugs do not have the socket and thus miss a letter in the part number.

For example, the letter “B” in “BPMR7A” and “WS” in “WSR6F” defines the thread diameter, and socket size of NGK and Bosch spark plugs, respectively.

Dimension Of The Sparkplug

The third letter of the part number shows the physical dimension of the sparkplug. Numerical values are not used; rather, a standard size parameter is used to show the dimension for this purpose.

However, most standard-sized sparkplugs do not use this term. The sparkplugs, which are exceptionally short and compact, use the term to specify the size.

For example, the letter “M” in “BPMR7A” of NGK defines the sparkplug as compact and shorter than standard sparkplugs. That is why there is no mention of size in the “WSR6F” of Bosch, as it is a regular sparkplug.

Resistor Construction

The term “R” in the part number of the sparkplugs reveals the construction type and material used for the resistor. Most widely used sparkplugs use a ceramic resistor built inside the structure.

Sparkplugs with a different resistor use a different letter or value to specify that. We can see the letter R present in both “BPMR7A” and “WSR6F” of NGK and Bosch in the presence of a ceramic resistor.

Heat Rating

You will find a numerical value from two to ten in the next phase. It defines how cold or hot the heating rating rates the sparkplug. A lower value indicates hotter sparkplug and wise versa.

The values seven and six means somewhat hotter and cold rating in BPMR7A and WSR6F sparkplugs.

Firing End Construction and Special Design

The last segment of the sparkplug part number shows a firing end construction and the presence of any special designs for improving performance.

Some sparkplugs have a shorter thread length for a small sparking position. Whereas most commonly used sparkplugs have a longer thread length for bigger parking areas.

Frequently Asked Questions (FAQs)

Are Bosch sparkplugs better than NGK?

The sparking duration of NGK sparkplugs is slightly better than Bosch sparkplugs. But the building quality and material used in Bosch are better. Overall, Bosch and NGK sparkplugs are equivalent in performance and durability. However, the longevity of the working condition depends upon the central and ground electrode material.

What sparkplugs does Stihl use?

STIHL power tools for lawn care use NGK sparkplugs by default. To be precise, STIHL uses NGK BPMR7A sparkplugs in their products. But it is possible to swap the NGK sparkplug with a compatible Bosch, Champion, or other brands of sparkplugs with similar configurations.

Are Bosch sparkplugs pre-gapped?

Bosch sparkplugs officially come as a pre-gapped one from the factory itself. The ground electrodes are very fragile, which increases the rate of sparkplug getting damaged due to after-sale gapping.


There are enormous models and brands of spark plugs in the marketplace, which can confuse an instance. Sparkplugs are one of the important comments that require occasional replacement as a regular maintenance program of a combustion engine.

Cross-checking the build quality and overall compatibility of the sparkplugs while a cross-brand swap is crucial. Now that you have the Bosch R10 to NGK compatibility chart, you can easily get the required NGK spark plug instead of Bosch.

We hope going through this article has been informative and let you know most spark plug part numbers to get your desired product easily.

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