Bosch Spark plugs
 

Time to tell the truth about Bosch plugs,Today I was on the phone with a rep. from Bosch, He was very considerate and listened to my story of spark plug dilemma of the DIYERS of this forum.He stated to me emphatically Bosch no LONGER MAKES A PLUG THAT IS NON RESISTER,so you do not have a choice of non resister plug from this company.I hope this will help you to make a selection from another manufacturer. The Auto zone people that sold me the plugs are getting an ear full from me and a letter to the head office,for telling a lie that could have damaged a very expensive part. Well I do hope that my former post on this will now stand corrected,And I do apologies for misleading any one.JNT:eek:

Bosch and Beru both make the OE spark plug for Mercedes vehicles that our cars require.

I wonder if the dealers carry the Mercedes Benz branded spark plug that is non-resistor?

I'v been having the same problem. I just went to MB dealer and they gave me W9DC0 plugs in lieu of the W9DC's that my manual calls for they were about $4.50 each. I dont know what the 0 is at the end but all I was able to find otherwize was WR9DC's, which I know are resistor plugs.

John Roncallo

Double check me, but I think the Bosch W9DC crosses to the NGK BP5ES. I've had good luck with NGK's in my ponton and others have spoken highly of the NGK's in other Mercedes applications.

Sokoloff is spot-on here... NGK is a great choice, Beru is OK too (didn't used to be, LOL), but they're much harder to come across.

That's and O and not a 0 (zero) and indicates a larger diameter center electrode.

first thing I noticed comparing my NGK vs Bosch (rusted rotten crap that came out of my car) is that the electrode size.

NGK is so much smaller it's in a whole different league. And you should know now, that the smaller the top, the more concentrated the spark and the more complete combustion.

bosch is a joke.

Yeah, kind of interesting how even Beru is generally considered to be a better product these days... that certainly wasn't always the case. Plugs made in India?? Even the Bosch wire sets are lower quality, caps, rotors and the like made on the cheap in 3rd world countries, etc..

I just picked up an '87 300E which I suspect could benefit from a new set of plugs. from these posts I get the opinion that NGK would be a better choice than Bosch. My experience with my 3000GT was that NGK coppers would last much longer and retain their performance characteristics far longer than Bosch. Does anyone have a recommendation for the 300 as to copper core, platinum or iridium?

Only use a copper core non-resistor plug.

I see a lot of NGK BP5ES being sold on eBay as a motorcycle part.

Yeah, BP5ES are easy to get, all over the net.

TR5 should be the correct plug for the 300E, BTW.

TRS is resistor.

Yeah, unfortunately that seems to be the only choice for NGK on a 300E. Maybe there's another brand option. The resisted plug isn't going to kill his car, though.

Most Bosch plugs are still made in Europe, they still specialize in Cu core and they still manufacture non resistor plugs up to this time. quality may have deteriorated for unknown/ no verification reason/s. All brand that has the same size as bosch can be used, plugs are plugs, their function is to spark and start the combustion, brands are just a psychological and marketing strategy. ask a professional electrical engineer. For langpfeife, as of today the best spark plugs are made in the 3rd world country, brands like NGK & Nippon Denso .

Japan isn't a 3rd world country (re NGK and Denso), LOL. India however is, and a ton of the Bosch plugs I see these days (especially non-copper core, but even those) are made outside of Europe. Doesn't necessarily make them "bad", I've used them on occasion, just an observation. And yes, like anything, plugs are made to different quality standards which can affect their longevity and performance.

I have has terrible luck with India Bosch plugs..insulators spinning in the case on several...BAD manufacturing/POOR quality control....

For many years, decades actually, I used nothing but NGK cooper, or Borch cooper and silver plugs because many have said platinum plugs are not as good. Couple years ago I tried a set of Borch Platinum +4 in my Porsche 944 and I was so impressed that I also put a set into my 928. A few months ago I decided to do the same with my 84' 500SEL. The Platinum +4 replaced a set of almost new NGK cooper plugs and once again they impressed. I have always heard that older Mercedes runs terrible with platinum plugs but it is not true in my case.

You are incorrect
 

Cool They do not still make a non resister plug!The reason for my starting this post was to provide the information,given to me by a rep of Bosch.I made the call to Illinois,and my request for information was taken,a few minute's latter a return call CAME TO ME FROM SAID REP.The man told me if I needed a non resister plug I would have to go to another manufacturer. So I suppose that would mean that BOSCH NO LONGER MAKES A NON RESISTER PLUG,. By the way plugs are plugs but the difference in putting to much resistance in the system can cause large expenses like the ignition control system.If you are going to change the manufacturers program,and use a non resister type of plug wire then you may get away with the resister plugs.I think I might be correct about this, But,well you know I think I am correct.JNT:silly:

Visit robert bosch.com and see for your self if they still manufacture non resistor plugs. Hope that puts your issue to rest.

I would rather base my comment on actual scenario than just a phone call to a stranger (rep) who may also be sending wrong information. mine is just to inform the truth cause R. Bosch still makes these plugs. they just delivered to my dealership over a week ago. If you REALLY need these plugs its available for sale unlimited quantity. (for the sake of argiument, I suggest you try purchasing from my shop and see whos right, your representative from Bosch or the Parts and Sales Department of R. Bosch, Germany.

Bosch plugs
 

You know the rep from IL. at the Bosch sight did ask me if I was a company or individual,perhaps that is ware the rub comes from.Info I got was not for a business,yet that still makes no sense,they ether do or do not make them so why would a company rep say no they do not,why would he not say only dealer or vendor supplied?So you say you got a delivery from R Bosch,maybe they or he should set the record straight,to the public. I can buy them from Phil too, but are they purchased from sources who are getting rid of stock that is out dated or are they from Germany or ware ever they are made now! This whole dang subject is filled with Frustration over your correct I am correct and who has the best info,you got yours from the horses mouth as did I so who knows!:kid:

spark plugs
 

Since all bosch plugs available are resistor type, I am in the process of finding a non resistor alternative for the e420. This has lead me to a few questions:
What is the difference between the Beru # BP5ES and BCP6E?
Different sources list different #'s.
Are the Beru Ultras resistor or non?

EDIT: Part # question above is for NGK plugs not Beru.

Bosch vs. NGK
 

I have been using NGK TR5's in my '88 260e and '92 300e for years with great results. Yes, they are resistor plugs, but still better than Bosch in my opinion.

One thing I have learned over the last 50 years of working on cars is that the only plug to put in an engine is the one called for by the manufacturer. There are exceptions like NGK BP5ES Bosch. This is really because the Bosch are harder to find. The exception above was learned when I needed some plugs and couldn't find the correct plugs so I went with NGK from advice of Mersedes Shop users. If I could find a good source of the Bosch I would still use them.

For years, I would only use Bosch plugs in my ponton and they always fouled. One day, a 308GTB Ferrari owner mentioned that I should try NGK as they never fouled in his car, even with city driving and the multiple Webers added to the mix.

My '59 220SE always runs a little on the rich side, and NGK plugs work better than anything else on the market, imho.

Now if I could only find some Packard 440 ignition wire.......