i really wish there was a definitive "which is best" answer about plugs on this forum.

seems like one plug works for one person and not for the another. i have read alot here doing a search and the consensus seems to be:

* Bosch plugs are no good...you lose power and mileage, they cause misfires,and they foul.
* copper works better than platinums...i read that plats can cause fuel not toburn right causing carbon buildupand can ruin your cat, they also foul.
* Autolite 5224's (OE) are equal to 3923's in these trucks unless you have lots of mods...
* Champion RC12 series areequal toAutolite 5224's which are both OE plugs...no negative replies about either plug
* hotter plugs work better for power and mileage unless you have mods,but if your motor is mostly stock you can get pinging, which can be resolved with a cooler thermostat...

with what i have read, the majority of people on this forum seem to be happiest with plain copper core OE Champion RC12'sor Autolite 5224's. so ithink its a guessing game and you try different things until you narrow down what works best for you.

after thinking more on all of this, my last 2 tanks of gas gave me 14.5-15.5mpg and i was getting 16-17mpg before the plug change. i know this mileage decrease is caused by plugs because this is all i have done to the truck in the last 2 or more tanks of gas.i think i am going to go back and change out the 3923 plats and put 5224's in.

 

If you're talking about a 4.7L, I'd use the Champion RC12MCC4. That's the OE plug, and the 4.7L V-8 engine is the ONLY engine to use that plug. Even the 3.7L engine uses a different plug. I know the Autolite 5224 is supposed to be the "same" plug as the Champion, but I've got the same issue with that as I have with the Bosch. There are just way too many "correct" applications for that plug for me to believe that it's optimal for ALL of them. Here are the applications for the Autolite 5224: http://www.sparkplugs.com/results_fitment.asp?pid=5224 Hint: the list is about 5 miles long, and includes such applications as a '95 Nissan pickup with the KA24E engine, an '08 Honda Pilot with the JA35 engine, an '89 Ford Probe, and even some Sea-doos and other marine outboards. I will simply never believe that this one plug is the optimum part number for every single one of those applications. It might be the best plug for some, and the not-so-best for others.

Now, if you're talking 5.2L, the OE plug is the Champion RC12LC4. Different enough from the RC12MCC4 to have a different Champion part number. But Autolite still recommends the 5224. Now, admittedly, the application list for the RC12LC4 is a bit longer than that of the RC12MCC4 plug (the 4.7L plug), but it's still within reason: http://www.sparkplugs.com/results_fi...sp?pid=RC12LC4 Summary: it's only used in Dodge 3.9L, 5.2L, and 5.9L engines.

So again, Ihave the same rhetorical question as I had above. Champion has two different part numbers for a spark plug for a 4.7L vs. a 5.2L. Autolite has one. Why? Champion is the OE supplier, and there was obviously enough of a difference to warrant that slight difference, whatever it is. Autolite was not the OE supplier, may not necessarily know what that slight difference may be, and specifies the same plug for use in both applications. Will you notice a negative effect if you use a 5224 plug in a 5.2L or a 4.7L compared with the "correct" Champion plug? Probably not. But we at least have to acknowledge the fact that Dodge did go to the expense (and it IS an expense) to define the properties, to do the procurement process, and at least initially stock, TWO separate plugs for these two applications.

What's the small, and maybe immeasurable difference in these two plugs...that Dodge thought was important but Autolite does not? I doubt any of us know...I know I don't. And that's precisely why I typically trust the engineering and R&D that Dodge did...rather than a generic cross-reference given by an aftermarket spark plug manufacturer.

 

dodge chose the best plug available10 years ago is all they did. technologies have changed. if they were so concerned with a spark plug, why didnt mopar make the perfect spark plug for that vehicle? spark plug manufacturers cant make a plug for every individual application. people try different things, and for some, they work, and for some they dont. im betting that if we went back in time to when these trucks were being developed there would be assloads of changes made and different parts being used...from what i read, the only difference between the champion RC12 series plugs is the length and they were changed in different years and vehicles on the same enginesfor emission purposes and good for emissions isnt always the best for performance. i have always believed that engineers go the safe route to save money on possiblewarrantee issues. they dont want people coming back in 30k miles and have to spend money on changing something even if the engine in question runs better over the short haulor doesnt last quite as long playing it safe. in other words, i think most companies do just enough to save their own asses and make something work "just good enough" until the warrantee runs out.the engineers did the best they could with what they had but times have changed and there are simple improvments that can be made with new parts that have come out since these trucks were made. people that have blinders on to new things never get anywhere. like i said, sometimes they fail and sometimes they succeed.

autolite plugs are as good as champions. the measurements and specsof both of those plugs are exactly the sameand just because 5224's are used in more applications than RC12's means nothing except for the fact that engine designers work around what is available parts wise. the different part #'s on championsare for different emission requirements for a particular engine and the differences are so slight that it doesnt matter or the engine manufacturer wouldnt recommendan autoliteplug in the first place.

there are a lot of people on this forum and all over the country that use autolite plugs and love them. i am not willing to call them all liars because dodge engineers decided to use a champion plug 10 years ago

 

I would submit that if the specs were exactly the same, the exact same Champion plug would have been used. And again...if the differences are so slight that it doesn't matter, why didn't Dodge use the same Champion plug? The engineers at Dodge weren't working around what was availble parts-wise...quite the opposite in fact: they were CREATING new part numbers. As stated, the Champion plug for the 4.7L V-8 isn't used anywhere else, in anything. That's not cherry-picking parts off the shelf. That's specifying new performance parameters.

This really wasn't the point of my post AT ALL. I didn't say anyone was lying, or that their experience with any plug wasn't believable. I simply said, and I'll repeat exactly what I said, "we at least have to acknowledge the fact that Dodge did go to the expense (and it IS an expense) to define the properties, to do the procurement process, and at least initially stock, TWO separate plugs for these two applications." Why'd they do it? You stated above, "the different part #'s on championsare for different emission requirements for a particular engine." I would like to know what the source of that information is. If that's coming from a Dodge powertrain engineer, cool...I accept that.

This discussion has really gone beyond what I intended. My point was simply that the OEM specifies the performance and operating parameters of a spark plug to a much higher detail than the aftermarket. When you said that the different applications for the Autolite plugs means nothing...that's exactly what that means. It means that the Autolite plug is supposed to be applicable to all of those applications. I didn't say it was a bad plug. I didn't say anything was wrong with it. I didn't call anyone a liar. My point was simply that it cannot be the optimum plug for every one of those applications. Somebody's getting a compromise somewhere. That's it.

 

Well, I have been doing some driving around with the truck since the plug change and milage has gone up a bit, but nothing to write home to Ma about. I usually tow my fishing boat anyway and the last run I aveaged about 15 mpg. We'll see how my Minn. fishing trip goes. Should only cost about $500-$600. THank God I'm splititng the cost with a buddy. We won't be in a hurry to get there. Better keep the speed limit.[:'(] My last run last weekend was eh, O.K. We had a 20mph head wind for 2 hours with an average of 15. On the way back with the wind behind, I was getting about 18mpg. I do have a topper on the truck as well, but haven't notice much change from with just the cover. I only have the topper for my fishing trip and camping type stuff.
I build a hoist in my garage with pullys. I can lift it on and off in less than 10 min by myself.

[IMG]local://upfiles/87199/F86CA3FA3C734934BF6FF9BF4FC1A39A.jpg[/IMG]

 

That's a nice setup in your garage! And 15-18 while towing with a 4x4 isn't bad. What do you normally get in town, without towing, and without highway cruising? I'm getting about 15-16 in my 1997, 5.2L 2WD.

 

If I putz around town I can get about 15. Not bad, but I don't drive it unles I have to. The last trip to MN for fishing I was getting about 13.5 on the way up and with a 40mph head wind about 9-10 on the way back. That was the longest 7 hours of my life.....

 

Iagree with JasonA. I went with theChampion plugs. I got them through partsamerica. I paid about $1.50/ea.

I changed them @ ~ 37k miles. My '04 runs like a Swiss watch now.

 

ok, heres the deal. i had the stock champion plugs in my 05 4.7 dak and they made the truck idle funny, come to find out that all the plugs were improperly gapped. at 30000 miles i went with the autolite 5224 plats. truck ran fine but i lost about 40-50 miles to a tank of gas. asked around and found that the 4.7 did not like plats. went with the autolite 3923 plugs and truck really likes them, one heat range cooler than stock, mileage went up better then the factory plugs, 18-19 around town 22/23 on the highway. also no pinging with terrible gas. now that i have installed a nitrous kit, went with the 3922 plugs and still have the same performance and no plug wear using the nitrous.

 

actually on the 4.7s they are a better built engine then the Older 5.2 5.9 and 3.9 engines..

the 4.7s can Actually get a better gain using planium plugs gapped correctly... the 5.9s 5.2s and 3.9s need to use the 3923s or champion stock plugs. (copper plugs)