What spark plugs should i use?

[Exnilo]

What spark plugs should I use in my 1992 525i automatic? I had bosch plugs in it and replaced them with some autolite platinums. Since then idle seems rough and is not really happy. What am I supposed to use? Thanks in advance!

[Bill R.]

ngk as seen here. I've had better results with ngk's in most cars.

What spark plugs should I use in my 1992 525i automatic? I had bosch plugs in it and replaced them with some autolite platinums. Since then idle seems rough and is not really happy. What am I supposed to use? Thanks in advance!

[ThoreauHD]

Bosch. If the plugs have too much spark, they get too hot. And hot is bad.

[joshua43214]

This should be an exciting thread =).

Over all the years of being a professional technician, my opinion on plugs has changed and evolved a bit. First off, unless you drive different than the factory expects, use the factory heat rating unless there is a service bulitin changing that. Find a plug that is right, then start fooling with heat ratings or gaps.

My experience with plugs are as follows;
Autolite: pure junk on every thing except a handful of american cars.
Champion: stout plug that runs perfectly on chryslers, but imports tend to disagree with them. I have seen alot of insulator cracking on high compression engines with these, I have also heard they corrected the problem. Run well in many VW's(OE on air cooled?).
AC: nice all arround plug, runs in most American cars well, German cars don't seem to like them.
NGK: Best Cu plugs I have ever seen, run on almost anything very well, last a long time. German cars like them. The platinums are very stout and seem to cross over well on cars that are OE Cu.
Bosch: the Cu plugs are decent, do well on German and some Japanese, American cars don't like them. The Platinum are a joke, you need a microscope to find the platinum, I have seen them wear out faster than NGK copper.
Splitfire: Junk, I have seen these cause horrible drivability problems and they often reduce performance. The handfull of cars they work in, they work well though.

Mixing up electode configuration can lead to troubles as well, aside from spark issues, I have seen plugs contact the piston tops when the wrong tips where used. Use the proper electrode configuration always, substiting a single ground or a 4 ground for plug for a double ground can lead to many troubles. Don't get cheap here, plugs don't get replaced much, pay the money and be grateful you don't drive a V8.

Keep in mind that the aftermarket lists plugs differently than OE, Generaly when you order plugs, the counter person chooses the brand, then looks it up in the book and sells you what is cheapest. So its easy to walk out with Bosch plugs, when OE is NGK. It is also common for them to sell you the "alternate" plug when they are out of stock of the OE plug. Best thing is to order by the part number and not the vehicle. I believe (someone correct me if wrong) some of the Bosch Platinum BMW OE plugs can not be sourced aftermarket as well.

My opinion is; if there is a choice between Bosch and NGK, use NGK, they seem to have fewer troubles. "upgrading" from copper to platinum will have a tiny difference that only a tiny handful of hard drivers will notice, for most people, it will lentghen the service interval. Plugs are replaced when they have a small rounding of the electrode and are a bit "polished" if done on the proper interval, this is before any signifcant fuel economy or performance reduction is seen, so upgrading can be an exercise in diminishing returns.

[632 Regal]

check carparts.com a division of JC Witney, got my bosch plugs for 1.99 each!

[Exnilo]

Thanks fellas. Changed to the NGK's and all is well in the world!