whiteminqua

I work at an Auto Zone. My store does not sell NGK. My customers have told me over and over.... Bosch Platinum is good, especially for imports, but not good in GM cars. Use AC Delco plugs in GM cars. DONT use any platinum plug if your car does not call for it. The cars work best with what they were designed with. For the most part, here is what we sell overall....


Bosch....
AC
Denso
Champion (not popular at all...)
Accel

Denso is not too popular here in central Pennsylvania, but they do sell a decent plug.

Oh yeah, the Plus 2 and Plus 4 Bosch plugs are trash.

CODY BEHNKE

*** Just a note ***

The new Rapidfires are a platinum plug now! They are no longer the preset gap piles of junk.

Sitting Bull

Now then, does that make any sort of objective sense to you?

Is there some sort of mystical problem with GM engines that they won't work with Bosch platinums plugs? Or is there a scientific reason?

Do you see how irrational that statement is?

The ONLY time to avoid platinum plugs is when using nitrous oxide.

Chuck!

I ran the Rapidfires in my 305 tbi with no noticeable difference over the normal Delcos. My uncle ran the +4's in his 4.3 Blazer and hated them. My dad ran the Bosch platinums in a 350 tbi truck and hated them, too. He went back to the $1.10 Delcos after 6 months and couldnt have been happier.

aklim

I don't like them for turbos either. I had a 89 Merkur XR4Ti that ran better on Autolites or Ford plugs than a plat plug.

On NA cars they do give longer life but that makes people less likely to take them out to look at them as opposed to the cheaper ones that should be done every year. Looking at them can warn you of problems that are occuring.

whiteminqua

Sitting Bull, I am basing my statement on experience of my own and on other mechanics. Cars that do not come from the factory with platinum plugs typically do not need them or respond well to their use. I am not an engineer, so I cannot tell you why. I deal with a lot of professional and backyard mechanics on a daily basis, and for the most part, it seems that spending your money on platinum (unless your car requires them) or specialized plugs is a waste of your dollars.

Likely, some cars will respond well to the platinum plugs. Keep in mind, GM and Delco are a family. The GM standard spark plugs worked best in my old Celebrity 4 banger. I tried Bosch platinums and they did not work very well. The car was designed for regular plugs. The concensus here when talking about 305/350 motors is similar. Look at how many guys here are saying use the Delco plug.

I am not sure why this seems to be true, but I am guessing that the newer cars have more advanced electronic ignition systems and can put out more power and consistently fire the platinum plugs. My work car is a 96 Olds Ciera with a 3.1 motor. The book calls for platinum plugs. Will I put regular plugs in it? No, it doesnt call for them. What will I buy? Delco. Why? The same company that makes the motors also makes the spark plugs.
Does this make sense now? Oh, I also checked to see what plugs a 95 Olds uses.... they were the standard plug.

Do you think that GM switched to the platinum in 1996 because of the OBD II sytems? Longer plug life? Less emissions? Mileage or performance? I am sure that it all plays a part in their decisions. Maybe someone online here can tell us a little more? I would like to know... what do you think?

Sitting Bull

There is only one significant difference between platinum and regular plugs. The platinum core, which creates a hotter spark and should more completely burn the fuel. It also lasts much longer because it stays cleaner, due to the hot spark.

People will always have preferences, for whatever reason. But if your engine is having difficulties running with platinum plugs it is likely due to some other reason than the plugs.

The worst plugs I ever used were Champions. They misfired right off the bat. A poor batch or inferior design and materials.

Bosch single prong platinums do not suffer from that.

82355

The reason older cars disagree with platinum plugs is that their igntion systems don't produce as much voltage on the secondary side of the igntion system (from the discharge of the coil to the plug). I am going to agree with whiteminqua. Just run regular AC Delco plugs. Multi pronged plugs are a gimmick to sell expensive plugs, they are right up there with a Tornado, and I hope none of you would put a Tornado on your car.

Martin

Sitting Bull

I don't know how you would define "older cars" but any HEI in good shape should have no problem sparking a platinum plug. My car is an 86 and runs fine.

ViperXx

Ok, here is whats happend so far. I've ended up getting ACDelco's Rapidfire plugs. Main reason being I could get the NGK G-Power that I wanted. I went to every automotive store in the city limits, nobody has them nor can they order them. All they had was regular NGK (non-platinum plugs), so, after thinking about all the information in this post (and in other places I've posted), I decided to get the ACDelco plugs, if I don't like them or I have problems, no big deal, I'll go to another brand next time I need new plugs. But on a side note, my other car, 1986 Camaro 2.8L V6, runs absolutely great with the Bosch +4 plugs, been running them for about a year now, no problems, but my v8 didn't seem to care for them. Also, step dads 96 camaro 3.8L 3800 series, it seems to run great with them too (has been using them for about 7 or 8 months now) and no issues on those 2 cars.

Thanks for everyones input.

ViperXx

Oh, also I forgot to mention, together we (including my parents) have 4 cars, 89 camaro, 86 camaro, and 2 96 firebirds (one green, one black), the green 96 firebird runs the bosch +4, runs with no problems at all, but the black one runs stock plugs (ACDelco Rapidfire plugs). They both run great (black one beats the sh*t out of the green one, thinking its a gear ratio difference or something, both cars should be stock though). Even that they both run different plugs, they both run without problems.