You can't go by the overhead computer, BTW. In my experience, it has never been accurate, always off by at least 1 MPG, usually 2 or so.

The best way is to do it as others suggested, miles driven divided by gallons put in.

Platinum plugs do tend to give our trucks rough idle issues. Iridiums seem to be OK (more expensive though), coppers seem to work best. Bosch plugs burn to hot supposedly, designed for foreign sports cars. I do know one thing, you can't index Bosch plugs as easily as others, since they have two or four (+2s or +4s) straps. E3 plus are the same, IMO, but others will vouch for them as well.

Do whatever makes you and your truck happy. Just make sure and run each set of plugs for several hundred miles, and reset the computer after change, to give yourself an accurate picture of what plugs are best.

 

OK here is my 2 cents. It doesn't matter what metal the spark plugs are made from as far as platinum and iridium are concerned. Those type of plugs use that metal so that they will last longer. A plus side to it is that allot of people think that a big fancy metal name means a better spark. This isn't true. The only reason they use those metals is that they last longer. There are some cars out there especially imports that require platinum or iradiaum plugs. This is because the plugs are a pain in the *** to change and so you need to put the long lasting plugs in so that they don't have to be changed all the time. Are trucks are pretty easy to change so coppers will suffice. As far as having more prongs on the spark plug all this does is get in the way of the flame kernel. It's difficult to explain the exact science behind it mostly because I don't quite have all of the details but, since I sell these plugs everyday I have about 3/4 of the Bosch plugs returned to me within a couple of months for warranty exchanges. People will come in and ask for Bosch and I will do everything I can to steer them away from them. If you have an import or a German car that burn almost no oil then I would run Bosch however you burn any oil you will fouled out the Bosch instantly.

My last bit on spark plugs. In a dodge truck I would prefer to see champion truck plugs or NGK. If you have done a little bit of tuning I would maybe switch to autolites just for the fact that you can easily adjust heat ranges depending on whether they are fouling or not. It's sometimes difficult to find champion and NGK in some of the other heat ranges.

 

Thanks for the input, guys. From what you're telling me, I'm leaning more towards leaving the copper Champions at least long enough to see if there is a consistant change for the worse. Would this be the best choice?

 

that would be the best thing you could do, also as jasonw stated, i would not go by the overhead, its not that accurate. And if its right, i wanna know how your getting that good of fuel mileage, i've never seen over 13.6 on mine.

 

This is true, but it is not the only reason. Some metals have higher electrical conductivity, especially inside pressurized environments, and can provide better spark. The reality is that when used in a properly running and tuned engine and replaced as per recommendations, it is rare that you will see the electrode worn away on even a cheap, standard spark plug. Much of the exotic metals sales pitch is simply hype.

 

I respectfully disagree. There are many cars out there that will not run right on copper plugs.

My brother's girlfriend's Toyota Camry, for example. The manual calls for these Toyota designed special platinum tipped dual strapped plugs. We tried running regular copper plugs (that the auto parts stores say will work), and the car worse than with the stock plugs that had been in there for 70,000 miles. We put platinum tipped plugs (but not the "special" Toyota designed ones) in, and it ran better. We traded those in for the official, Toyota recommended "special" plugs, and it runs fantastic.

I've also heard of the newer Hemi engines, for another example, not running right on regular copper plugs, but only the platinum tipped units (or better).

I do agree with you on the three or four straps, though. One or two is plenty. Any more and your just throwing it in the way of the fuel.

Yup, the metals do conduct better, which is the reason, I believe, that some engines almost require them and tell you not to use regular copper plugs. There is a lot of hype, you're right, especially for our slightly older trucks, but some vehicles are designed for these metals, and not copper.

 

I just filled up today and calculated 12.7 mpg. That fuel was burned primarily with the old plugs. Next time I fill up, I will see if there is any change. You guys are defniately right about how inaccurate the computer is though. It was saying 14.3 and recently 13.7 (trips to the city).

 

I was running Autolite 3923's and I just recently needed to replace them. I went with the NGK V-Power, and my truck seems to really like them. Haven't really noticed much difference yet in mpg, but don't believe it's gone down any. They were about $18 for all 8, so that isn't too bad, either. I wasn't overly impressed with the 3923's, and they don't last long enough IMO.