HI, I raplace the spark plugs with Bosch +2 on my 89 GP last week and notice less "mpg" and went to buy some at autozone for my brother's 85 astro and the guy told me that he did not recommended German brand to use with an american car not even japanese car because will burn more gas and I will have problems and a mechanic that was there said the same he recommended ac, autolite and other because German plugs will burn more gas and after 3000 miles the car will start doing funny things because the voltage on the Bosch plugs is not right for an american car.

What do you thing should I replace the Bosch spark plugs?.

Yes, can the Bosch spark plugs and go with either AC Delco or Autolites.

I generally recommend to those who I send them to that they run AC in a GM, Autolite or Motorcraft in a ford product, Champion or autolite in a chrysler, and NGK or Bosch in an import. For some reason and yes a plug is a plug is a plug but that seems to be the way each works best. Other than my briggs and stratton, Chry is the only thing i put Champion in.

I agree with Bob, get the autolites or ac delco plugs. The bosch plugs do not work well in most American cars. The +2 and +4 plugs are just a gimmick to make money and really don't do much to improve performance or fuel economy. Of course someone will argue with me on that but that's my 2 cents on the subject!

You can recommend all you want but I disagree on your GM solution. :-) It is a misconception that Autolites don't work or are not good in a GM product. I have used them for several years and continue to use Autolites in my Grand Prix. The NGKs work fine too. For example the AC Delco 41-101 Iridium is made by NGK.

We have debated this issue over and over in this forum. We do all agree on one thing - Bosch spark plugs are garbage.

BTW - I use Autolite Platinum AP 606 in my wife's '99 Regal LS (Series II 3800) and we get 22 - 23 in city and over 28 highway. Never misses a beat.

Personally I go with the AC Delco Irridium plugs. They may cost a little more than your average plug, but thay last a long time and have excelent performance.

And yes, Bosch are trash.

ditto on the bosch's. they worked great on my 5.0, but they were hell on my civic. i didnt know how bad it was running till i changed them. also, ngk's are great plugs too. you cant hardly go wrong with them. the ac delco iridiums are worth their weight in gold to the gp.

I think Bosch is German for CRAP, but I could be mistaken, :-) . Autolite actually makes AC Delco plugs for GM when their own facilities cannot meet demand, so they are an excellent second choice. Most Delco platinum/iridiums are made by NGK as Bob stated, so the lines are blurry as to who makes what for whom. One thing is for sure, most (if not all) of us think very lowly of Bosch plugs and oxygen sensors.

It kinda baffles me Bosch has got such a bad rap. Maybe their plugs and sensors are junk, but I'm more involved in the diesel side of the automotive world and Bosch fuel injection systems are top notch.

I do have Bosch 02 sensors on my car and if I was around this forum before I bought them I might not have, but I'm not having any problems with them thus far. I do agree that AC Delco is a great OE supplier and it's always best to go with them if possible.

I don't know Rich. Personally, I'd qualify that statement. Robert Bosch does make great automotive stuff like fuel injection systems, suspension controls and braking systems. The last time I checked that is what Mercedes and BMW uses.

As far as their spark plugs and 02 sensors I agree.

However, in the old days the Accel performance spark plugs (Yellow Jacket) were made by Bosch and they worked fine as long as you used the Accel ignition coil. I had them in my '70 Dodge Challenger with 440 Magnum but that is ancient history.

The golden rule is to use the manfactures oem type spark plug that the good book calls for.
Study your spark plug books.
Autolight may work well at times but beware and take care.
Autolight plugs does not have all of the correct and different applications and ranges that motercraft or ac-delco or champion does.
Depending on the engine and ign system they do not match all ranges.
Look at a motercraft book then look at a AC-delco spark plug book.
They have about twice as many different plugs than autolight does.
And yes NGK and ac-delco and GM may be in bed together. Some GM truck plugs are factory oem NGK plugs .
Bosch plugs are mostly crap but Bosch does make a lot of factory OEM 02 sensors. Pull a factory 02 sensor and have a look. The Bosch stamp will be on a lot of them along with a OEM part no.also.
MT
MT

Is this a general statement or specific to a Pontiac Grand Prix like a modded GTP? Because I disagree. The Autolites specifically the copper core are the defacto choice for us Hot Rodders with GTPs from '97 - '05 models. Knock retard (KR) is a concern and most of us run smaller supercharger pulleys along with a host of other mods. Very easy numbering system that you can actually memorize. For example:


For Series II/III 3800 L67:

stock = Autolite 606
one range colder = 605
two ranges colder = 104
three colder = 103

Now explain to me what AC Delco has relative to the above for example in the 41-101 Iridium spark plug (stock) to colder ranges?

BTW - The AC Delco 41-101 Iridium is used in a wide variety of GM engine platforms as an OEM plug or recommended replacement. I have them installed in my stock '01 Regal GS with SII 3800 SC and '02 Olds Alero with 3.4L V6. Doesn't sound too engine or ignition specific to me.

Quote from bnaylor3400
Robert Bosch does make great automotive stuff like fuel injection systems, suspension controls and braking systems. The last time I checked that is what Mercedes and BMW uses.

I wonder if this is why BMW and Mercedes were BOTH in the bottom five for new car dependability.

lol. :-) You may have a point Rich. But that has been a trend for 4 years on Euro cars. You must be referring to the new Consumer Reports which had all the Japanese and Korean mobiles ranked with top honors. And is it really due to Bosch stuff? I didn't see where the BMW was in the bottom of the dog pile.

http://www.cbsnews.com/stories/2006/...n1361945.shtml


After Lexus, Honda and Toyota, the brands rounding out the top ten for reliability were Mitsubishi, Subaru, Acura, Scion, Mercury, Mazda and Suzuki. The ten lowest-rated brands were Audi, Infiniti, Saturn, Lincoln, Jaguar, Mercedes-Benz, Volkswagen, Land Rover, Hummer and Porsche.

The autolite does not match all specs and heat ranges was a general statment for all big 3 cars manf.
Chech your spark plug applications and books. Autolite give only one plug no for several different applications to where some other brand plugs give 3-4 different no. or different applications
Based on general tune up and repair work I have done over the years.
Autolite runs and works good and matches motercraft and Ac delco and champion in some and some they do not.
And I have run to a few cases where the factory OEM Plugs or what the spark plug book calls for did not work good.
High performance engine fall into a different ball of wax that I am not into.
And if you check the latest AC-delco book they call for 41-984 on the 01 regal 3800 vin K and 1 reg and SC engine.
Strange deal because a 00 and 02 calls for 41-101 spark plugs and the factory OEM ac plugs were ac delco 41-921.
And do not ask me to figure that one out. That is just what the good ac delco plug book says right or wrong.
Also Ac delco has well over 10 different plug type listed on later GM engines.
MT