I think your car also has the NGK of Bosch Platinum with 4 electrodes. The philosophy behind that, it the electrical current, most of the time will chose a electrode with less resistance.

To make a long story short, 4 electrode plugs--> a longer interval for changing plugs ( better for consumer)--> plugs in some circumstances not that efficient anymore-->after so many miles, higher fuel consumption and most important Loss of Power.

I change plugs way before 30 K miles. If you can DIY, you could consider change to high performance plugs with 1 electrode , but be ready to change every year or 10 or 15 K miles. I stick to the OEM and change every 2 year. Fuel price is insane in Europe, thats why Did some math and 7,9 US Dollar a Gallon.

Do what you feel happy with

 

Hmm good to know, I will check out some HP Plugs and do it this weekend (maybe, I might want to see what that long drive will do to MPG ) Either way it looks like I am going to be changing some plugs. Now to go find some good HP plugs to do it with

 

So, the condensation that was coming out from my exhaust is not normal? How do you prevent this? Is there any maintenance that I need to do? Thanks!

 

I had this exact thing at about your mileage. I was down to 14 MPG!!!!!!!! I replaced my spark plugs with new NGK Iridium plugs and also did the $140 BMW Fuel injector service at the dealership. After that my car was at 23 MPG!!!! It was a HUGE difference.

 

When the exhaust pipe is cold, water vapor will condense as the exhaust cools on the pipe. After the pipe heats up, the vapor will not condense. Remember that the combustion of hydrocarbon fuel produces both carbon dioxide AND water vapor as a normal part of the process. All gasoline engines produce water vapor and all water vapor condenses if the exhaust pipe is cool.

HOWEVER......If it's running out of the tailpipe all the time after the car has already warmed up and you're losing water from your cooling system then yes it is not good. It may be a blown/cracked head. And no, this is not good. If this is the problem, it would be a major rebuild.

 

Nope I only have condensation when it's cold. When it warms up it's fine, besides I have CPO and Maint warranties - if the engine blows I am out $50

 

I am going to check into Howie, thanks - NGK Iridiums IX are about $6/ea near me, pretty cheap insurance really

 

I feel the same as you JOhn. It seems my gas consumption has increased and am wondering if I should replace my plugs since I'm at the same mileage as you. Ross and I were thinking of doing the DIY for plugs.

 

I would do it DIY if I were you guys too, it isn't hard and there is no sense paying someone else to do it.

 

The DIY's look to be pretty easy, but I think having the right tools is what's key, as is the case for most jobs right?