Dropping MPG

Billy ray, not only will the mileage drop, but it will quickly start missing at idle with those fancy plugs in it. 4 mini posts just don't produce a nice fat spark the 4.0 likes it would seem. Same for the 'splitfires'.

I have fixed a whole bunch of bad idles and bad mileage by simply tossing the 'new' bosch plugs in the trash.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >

The regular Bosch Platinum plugs just have the one post, just like a regular spark plug. The only difference I know of is the center electrode down where it fires is platinum instead of copper.

Seeing how I change plugs every 2 years anyway there probably isn't much justification for the platinum....

If the +4s are causing him a rough idle Bosch will buy them back

I run plain copper spark plugs. Either Champion or Autolite. Actually I think the Autolite are better made. The fancy plugs do nothing but waste money. With one exception. The platinum (non fancy) or Irridium plugs do last a lot longer and don't gap out. The only real reason to use them is if getting at the plugs is a pain in the arse. For the I6 it's just too darn easy to change plugs and looking at the plugs is the best way to catch engine problems.

my .02 quatloos.

I like the way the manufacturer has done vehicle testing with OEM plugs. One thing I learned at Microsoft is that tested combinations work, and untested combinations don't work. With respect to spark plugs, tiny little differences in heat range will affect gas mileage, plug life and maybe even engine life. I have heard some horror stories about platinum plugs in non-OEM applications. I will be putting platinum in my wife's CR-V, but that's what came in it. I put Champion in my Jeep, non-platinum NGK in my Civic, etc.

Earle

Doug,

You have too much time on your hands! Jsut Kidding I thought I was the only one that keeps records like that. I use to do it in a log book until I got a computer have been doing it in XL ever since. I even put in the maintenance/parts costs and can look at the overall costs for the live of the vehicle. I even keep the log on my lawn equipment with two file draws of OEM manuals of everything else. Coasty

:)

It's a hobby.

I started the log just to see if the vehicle actually got the milage shown on the sticker. Then I just wondered how milage fluctuated over summer/winter. Then I wondered about octane and if higher or lower made any difference (apart from cost).. It sort of grew from that.

It's kind of amazing what you can do with excel. I've built some spreadsheets for work that do a lot of number crunching.