How often should you change spark plugs?

[Al Gray]

I have a 1992 525i with 181,000 miles on it today. I last changed my spark plugs in June 2003 with 145,000 miles. The car seems to run okay but would I benefit from a fresh set of plugs? I know plug life is a lot longer than it used to be. What are your opinions?

[Adnan]

...and use stock Bosch plugs.

Regards,
Adnan

[uscharalph]

I was just checking the PO's repair records and my spark plugs were changed @ an Inspection 2 on 9/29/01 (38,642 miles ago). That's also when my fuel filter and timing belt were changed.

Next project in a couple of weeks: New spark plug wires, spark plugs, distributor cap and rotor.

[632 Regal]

hmmm...mine have about 40k on them, I read somewhere that these last a long time...I should take a look at them one of these days to see if they are worn

[winfred]

after 30-40k they are getting pretty worn

[Anton CH.]

No reason why platinums shouldn't last longer than that.

[Rick L]

I change my plugs every 30k miles. I use the factory Bosch Super plugs. I tried the Bosch Platinums and they were very disappointing so I returned them (even I installed them, the store took them back since the clerk said it is common that many people return these). Local performance shop told me that the Bosch Platinum is in FACT inferior to Bosch Super. They never use them because they get many complaints from customers with Bosch Platinum. They highly recommended NGK plugs. Yes, you should put Bosch in German cars and NGK in Japanese cars but they said the NGK makes the best spark plugs and once I use them I would stick with NGK. I'll give NGK a try next time.

[granit_silber]

I have a 1992 525i with 181,000 miles on it today. I last changed my spark plugs in June 2003 with 145,000 miles. The car seems to run okay but would I benefit from a fresh set of plugs? I know plug life is a lot longer than it used to be. What are your opinions?

Not to hijack the thread, but is it okay to unscrew the plugs and remount them? The Bosch Platinums I bought had little rings I assume to be crush washers around them.

-ashley

[winfred]

yes you can remove and reinstall, just becareful not to overtighten


Not to hijack the thread, but is it okay to unscrew the plugs and remount them? The Bosch Platinums I bought had little rings I assume to be crush washers around them.

-ashley

[winfred]

the bosch platinums suck because of the tiny center electrode, it doesn't take much to fowl it, it doesn't matter how many ground electrodes they put on it it will allways be a piece of ****


[B] Local performance shop told me that the Bosch Platinum is in FACT inferior to Bosch Super. They never use them because they get many complaints from customers with Bosch Platinum. B]

[Gayle]

the bosch platinums suck because of the tiny center electrode, it doesn't take much to fowl it, it doesn't matter how many ground electrodes they put on it it will allways be a piece of ****

Winfred tell us what you really think.

[632 Regal]

Do Not Change Them With The Engine Hot Or Warm...warning Said!

[632 Regal]

anything other than the stock supplied plus will **** up... case closed, get some stocker Bosches or forever hold you piece.

[ryan roopnarine]

as somebody that drives an @ssload a week (700 mi +) on the same engine as you, at 40k they are ready to die (manifested as slight misfire or lope in idle). change them.

[632 Regal]

you know im messin. We all know you take the bus.



as somebody that drives an @ssload a week (700 mi +) on the same engine as you, at 40k they are ready to die (manifested as slight misfire or lope in idle). change them.

[Jean@MtMiguel]

'91 525i "ignition system fires specially designed, triple-electrode spark plugs, w/c are development of BMW, Bosch and NGK" these are excerpts from VW & Porsche and European Automobiles March 1991 issue, I still have this copy, with Bosch Plus 4's I am using, I'm just one electrode over as specified for this engine.

[Interceptor]

I have a 1992 525i with 181,000 miles on it today. I last changed my spark plugs in June 2003 with 145,000 miles. The car seems to run okay but would I benefit from a fresh set of plugs? I know plug life is a lot longer than it used to be. What are your opinions?
Get yourself a set of Denso Iridum spark plugs - they have a laser-welded 0.4 mm iridium electrode and last over 60,000 miles. But be warned, they're extremly expensive. I payed $135 for a set of 6! Maybe in US they're cheaper.

[SRR2]

Yipes.

I guess I don't see the point of spending this much on plugs. The car won't run any better on them than properly-gapped OEM plugs. The OEM plugs can be had for $2 each if you shop around, and they'll last at least 30,000 miles. So what you accomplish by spending the extra $120 is to avoid an additional $12 in plugs and the 15 minutes it takes to change them. Doesn't sound like much of a deal to me.

BTW, I've used the Bosch single-electrode platinum plugs for years in both cars with very good results. Never fouled or any other problem. The only advice I have about them is that they need to be gapped to .040" instead of the specified .024" (IIRC) otherwise the idle gets really rough. And, to top it off, with sale prices and rebates, I've never paid more than $1.50 for any of these plugs.

[Interceptor]

I guess I don't see the point of spending this much on plugs. The car won't run any better on them than properly-gapped OEM plugs. The OEM plugs can be had for $2 each if you shop around, and they'll last at least 30,000 miles. So what you accomplish by spending the extra $120 is to avoid an additional $12 in plugs and the 15 minutes it takes to change them. Doesn't sound like much of a deal to me.
Well, you obviously never tried Denso Iridium. :) I was also very sceptical - I first tried them in my motorcycle - it only had one cylinder, so it wasn't much of an expense. I was VERY satisfied how they performed. After that, my friend put them in his bike and later in his '97 E36 320i with M52B20 and was very satisfied. I had no excuse, I went Denso in my car, too. :)

[mikell]

It's PEACE, my friend - of course, you can hold your piece too, just don't do it in public.

[SRR2]

With all due respect, this isn't much of an objective reason to spend this kind of money on spark plugs. Now, if you had data on how much smoother the idle was, or how the gas mileage improved 38.749% with the high-dollar plugs, or at least *something* that's objectively reproducible, I'd be more interested. But what you offer here is a bit too subjective for my skepticism threshold.

[Interceptor]

With all due respect, this isn't much of an objective reason to spend this kind of money on spark plugs. Now, if you had data on how much smoother the idle was, or how the gas mileage improved 38.749% with the high-dollar plugs, or at least *something* that's objectively reproducible, I'd be more interested. But what you offer here is a bit too subjective for my skepticism threshold.
Everything improved SLIGHTLY but NOTICABLE. The point is - it all depends on how much money you are willing to spend on a overall slight improvement.

[ve39]

So after seen this thread i think i should change my is there a tutorial on how to do it in 525i and what bosh plugs shell i get

[Bill R.]

results are obtainable if you poke around on denso and ngk's website, they both have or had in the past independant lab tests verifying the gains with the iridium plugs... that plus the fact that all of the new hybrids that i've looked at so far have had iridium plugs in them. Honda and toyota both have a specific part number for each iridium plug that they use. In their search for better fuel economy they used iridium plugs and they are individually indexed for each cylinder, that why spark plug 1 will only work correctly on cylinder one spark plug 2 , cylinder 2 etc.... The question is , is the mileage and power gain worth the premium cost of the iridiums? Autozone was selling the iridiums for 10 each trying to move some of the to get some positive word of mouth out on them. The gain that the manufacturers claim is small, something on the order or 5% but it is a gain for those seeking the most. I personally haven't tried them yet or had any of my customers try them. I have replaced them in the newer lexus rx300's that they come in stock.
And i suspect on the bosch single platinum plugs that your one of the lucky ones. I can give far too many examples of problems with them and many other mechanics that i know have also ran into problems with them.
A specific example was back in late 85, early 86 when bosch first came out with them for general auto usage with the small center electrode. My brothers in laws auto shop had a distributor who made them a special deal on them to encourage them to start using the platinums in customers cars. They installed a large number of them in the first 3 months or so , at least 150 cars worth, primarily american cars , gm products with hei. After about the first 3 months they started having many of their customers bringing cars back with missing stumbling problems etc... it turned out that the small center electrode was eroding away very quickly on the hei cars and recessing causing the misfiring problems when the gap got too large. And over the years i've run into many problems with them fouling out on cars like the m30, I have the best results on them with the bosch super and ngk regular or v groove plugs.






Yipes.

I guess I don't see the point of spending this much on plugs. The car won't run any better on them than properly-gapped OEM plugs. The OEM plugs can be had for $2 each if you shop around, and they'll last at least 30,000 miles. So what you accomplish by spending the extra $120 is to avoid an additional $12 in plugs and the 15 minutes it takes to change them. Doesn't sound like much of a deal to me.

BTW, I've used the Bosch single-electrode platinum plugs for years in both cars with very good results. Never fouled or any other problem. The only advice I have about them is that they need to be gapped to .040" instead of the specified .024" (IIRC) otherwise the idle gets really rough. And, to top it off, with sale prices and rebates, I've never paid more than $1.50 for any of these plugs.

[Russell]

I changed mine at 31,000. Plugs were very clean just worn. The sides of the electrode were quite worn.


after 30-40k they are getting pretty worn

[Gene in NC]

Whenever you want car to run better and whenever the old plugs are out for any reason. '89 525 174k wasn't running too badly but took a peek and found NGKs were highly carboned up and wet looking. Changed to proper Bosch and reset the ecu.

Boom! Smooth running, better power and 10% improvement in MPG.

[Bill R.]

So they too qualify as the proper plug....




.
Whenever you want car to run better and whenever the old plugs are out for any reason. '89 525 174k wasn't running too badly but took a peek and found NGKs were highly carboned up and wet looking. Changed to proper Bosch and reset the ecu.

Boom! Smooth running, better power and 10% improvement in MPG.

[Gene in NC]

Bill, PO may have been lugging around town in fifth with NGK, using 10w30 Castrol, and getting 750 miles per quart. I changed plugs to Bosch oem, and oil to M1 15/50. Plugs after 1kmi were beautiful and oil use dropped to 1/3 qt per 1,000 mi and mpg jumped more that 10%. Problem may not have been the NGKs but I'm not going back to find out.

Couldn't ask for much more.

[shogun]

http://hometown.aol.de/Imamark/CIMG3078.jpg
http://hometown.aol.de/Imamark/CIMG3079.jpg

We removed them last saturday from a friends car as the engine was running rough. So we changed dizzy caps+rotors, all 12 plugs (unfortunately he wanted again the platinum), 2 new oxy sensors, but the engine still runs rough in idel. Wonder why the thread is oily. Don't know if the previous owner used some oil/grease when he put them in. Outside of the thread there is no oil. So it does not come from outside but from the cylinder.
Also noted that the 2 plugs on the right have a different color that the others.
I will check tommorow for air leaks in intake system.
If any other ideas, let me know.

[Jean@MtMiguel]

What part of Japan you're at? I've been to Tokyo years back, surprised that cars stopped at major intersection turn off their headlights just their parking lights on .Is that for consideration of not blinding cross traffic? Domo Arigato