I'm getting confused about this thread. I use BP5ES (no F) in my 500 which is a 117 engine. The BP5ES is the crush washer type.

Have I been wrong all these years. I have put at least 4 sets of BP5ES plugs in over the last 12 years.

If you have a tapered seat plug in your 300 now than I believe you need the BP5EFS plugs.

PaulM

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84 500 SEL (307,xxx miles)