I'm about to replace the spark plugs in my ML500 and the auto parts store sold me Bosch 6702 (FR 8 DPP30X) spark plugs. I took a look on Fastlane and the plugs they have listed are all Bosch 7422 variants.

I couldn't find out what, if anything, is the difference between them?

Anyone have any knowledge in this? and if I can use the 6702 plugs?

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1992 Mercedes-Benz 400E
2002 Mercedes-Benz ML500

The OE plugs were double platinum, and the 7422 is double platinum, it's your equivalent replacement. The 6702 is only single platinum (center). It will *probably* work, but it will wear out far more quickly. It's not an awful job, but I wouldn't want to change the plugs twice as often. (I'm not sure where you got the conversion number, but it's not accurate; Bosch's own site notes the 8100 is double and the 6702 is not.)

If you want the fine wire, you'd want the 8100. I don't know anyone who has reported an issue with the 7422, though, and absent a sale or coupon deal, it's the least-expensive plug that meets OE specs.

If I may, I'd suggest testing and inspecting your plug wires as you change the plugs.

Good luck.

Ok, I see. The life of the spark plug itself is going to be the main factor here, if I use these plugs (6702) I'll just be back under the hood sooner than later. From a little more reading into the subject it seems like they will deliver the same performance just have a shorter life span.

@ Can't Know - what do you mean by conversion number?

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1992 Mercedes-Benz 400E
2002 Mercedes-Benz ML500

The conversion number is the FR8DPP30X. In Bosch's legacy numbering system the "PP" means double platinum, but the 6702 is single platinum. Bosch has created the confusion by changing the numbering scheme, but in any event that's a single platinum plug. (I'm guessing you found that number through an online reseller/vendor, and those conversion catalogs are not the most reliable.)

By using the single platinum plug you're reducing the interval to somewhere between 30,000 and 50,000 miles. The other issue is that the side electrode is going to wear faster, so your gap will deteriorate faster, and your mileage and performance will fall off as that happens. When it will first be noticeable is a good question, and due to the ECU compensating as it happens, you might drive several thousand miles before you catch it. In the meanwhile you'll have been suffering a loss of performance and mileage, which by the time you then change them may actually cost you more than using the correct plugs to start with.

Given that the only reason I can fathom to use the unspecified plug is to save a few bucks (roughly $50 on the V8 engine) -- and that you're already saving hundreds on the labor by DIY, my personal opinion is that sticking the 6702 plug in there is being penny-wise and pound-foolish.

That one of the best things about owning a vehicle is getting to decide the best way to maintain it, and my goal here is to get your eyes all the way open so you can make an informed decision, not to browbeat you into conformity.

Good luck with it. Assuming you're keeping the truck, please keep a close watch on the mileage and update us as you roll up some miles. If it turns out they are a solid deal all the way to 50K, then for many people that might be a good alternative.

I found the FR8DPP30X number on the box to the spark plug itself, it's printed just below the 6702. On the box though it only states the it is indeed platinum and not double platinum, guess they've made a change of what the code represents

Everything you've spoke about make perfect sense, if I would have known that the lifespan and performance was a real factor then I would have picked up the double platinums in the first place. I'm going to return these and pick up 7422 plugs.

I was thinking that the whole double platinum thing was more marketing than anything, it's good to know that its not. The +4 plugs come to mind...

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1992 Mercedes-Benz 400E
2002 Mercedes-Benz ML500

The +2 and +4 seem to have their uses, though one of them appears to be adding confusion because when someone says "double platinum" that's what some people may think. IIRC the (+) series are single platinum (center electrode) and the side electrodes are conventional. I've heard some people swear by them, and others (particularly with these dual-plug, sequential-fire engines) swear at them.

It's curious that you got that conversion from the box. Is it a stick-on label? I'm wondering if that was something the store might have mistakenly put on. Many years back I worked in auto parts and when companies did this they'd send labels and instructions -- which often were great, and often not. Or, perhaps, Bosch has managed to confuse themselves with their new scheme.

In case you care for the sake of abstraction, Bosch also does this with their iridium plugs. There are iridium, double iridium and one that is like a hybrid, where the center electrode is iridium and the side is platinum. Why? Probably marketing, so you have a plug option in every dollar segment.

Me? Personally I'm waiting for plutonium plugs. They glow in the dark and don't even need coils or wires.

That conversion is from the box, the individual box. It's printed directly on the box along with the 6702.

Too many choices...

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1992 Mercedes-Benz 400E
2002 Mercedes-Benz ML500