i replaced the sparkplugs for the first time in my 05' feh. i have 99,375k on it. i replaced the factory plugs with the bosh fusion platnium plugs. has anybody else used these plugs before. if so how is it running mine runs great!. i just replaced about 3 or 4 days ago.

 

Wow, you take your maintenance schedule pretty literally. How did the plugs look after 100k miles?

I've always had best luck with Motorcraft plugs in Ford vehicles. I used the Bosch plugs in one of my trucks once and took a big enough mileage hit that I switched back. Hopefully you keep close enough track of your fuel mileage that you will be able to see any dfference (better or worse).

 

I tried Bosch +4s in my Mustang and lost alittle mileage, on the order of 0.2 mpg on a scale of ~26 mpg for the big V-8.

There is a very specific procedure to follow so that yu don't damage the aluminum heads. Any problems getting the old plugs out?

 

i will post pictures of the old plugs i soon as i upload the photo's from my camera. as for the plugs themselfs they came out at little hard at first then they easy after that, but i used the never seize they sold me with the plugs so next time they will come out easy.

 

I noticed where the plugs go in is a cavity that holds water.
As such, the top threads of my old plugs were a little oxidized.
Not rusted, ( not iron ) but were a little hard to get out.

I put in the Bosch +4 because it was what was available on the shelf the day I wanted to change them. Did mine at ~75,000 miles because I was getting a rough idle when cold. Seems to have cleared up the "problem" the past 10k.

Stock plugs have the Irridium tip. Probably just a gimmick. But those cost a lot more.

 

You know, after playing around with plugs on my two high mileage cars (383,000 & 254,000 miles each), I concluded that you need to try out plugs for the specific engine and choose what performs best in that engine.

I just did not see any pattern to the performance on any given plug. I tried plugs for 50,000 miles each and changed them. Just did not see the improvements I had hoped for. No pattern.

Any different experience out there?

 

I think most people who see improvement with a new type of plug, see that improvement because they replace a dirty one with a clean one.

In reality, you need to run 1 tank with a new clean one of the same type, then run 1 tank with a new one of different make/type and repeat for multiple cycles over all seasons.

Now, who's got the time to do that?

I can't prove the Bosch +4 cleared my rough cold idle, or just changing plugs did.

 

I track mileages (I just write the odometer on the receipt)(even my kids got it as teenagers, you know, no odometer on the receipt, no keys, they only forgot once...). So when I speak about spark plug performance I'm talking of performance across 30k-50k miles on a given set of plugs.

When you take a car out to 383k miles you are able to compare spark plug performance like that. I put Bosch +4s in the Suburban and the fuel mileage dropped by 0.2 MPG on average for example.

My spreadsheet goes back to purchase on each car.

 

I changed the factory plugs on my 06 FEH to Bosch IR Fusion plugs at about 70k miles. Noticed no statistically significant MPG change, but it's hard to say since the temps here in Texas have ranged between unbearably hot to reasonable and AC usage has also varied.

The factory plugs looked great. There was a slight bit of oxidation on the top of the factory plug threads as gpsman1 noted on his.