Gas mileage goes up with new plugs???

[MD5]

I hit 40k miles, and figured (even though not reccommended by owner's manual) that I'd replace the plugs.

I had been getting about 155 miles at 1/2 tank pretty consistently. I changed to Autolite Platinums and immediatly noted a 20 mile increase. So where I was getting 155 miles, I'm getting 175-180 miles per half tank.

The OEM plugs have a very small electrode, but looked great for 40k miles. I'm just wondering if the tiny electrode makes for a thinner spark. We all know that a generous spark will ignite the air/fule mixture better.

I was wanting to post this up and see what take others had...

 

[AIMWO4]

I've noticed improvement on previous Toyotas I've owned. I only have 8K miles on my 5, so no new plugs yet.

 

[MD5]

I've got about 42,600 miles now, and the trend continues, so it wasn't a fluke.

I think from now on I'll change the plugs about every 30k. It's less than $10 per set, so its cheap insurance.


30,000 miles / 45 mph overall average speed = 666.67 hours
666.67 = 40,000 minutes
40,000 minutes x 2,300 rpm = 92,000,000 / 4 cylinders = 23,000,000 firings per plug.

So, I guess that's not unreasonable to change the plugs at 30k miles.

Hell, I'd be tired after 23mil reps....

 

[AIMWO4]

Hmmm... maybe it's worth doing now... considering gas prices. (spin)

 

[07MZ5SA]

Spark plugs are somewhat worn after 35K even with platinum or iridium.

I will stick with iridium replacement since small electrode=stronger/precise ignition for MZ5's high revving engine.

 

[MD5]

Spark plugs are somewhat worn after 35K even with platinum or iridium.

I will stick with iridium replacement since small electrode=stronger/precise ignition for MZ5's high revving engine.

The fastest my engine sees is 3,600 rpm at 75mph. I NEVER hit 5k, so I can be satisfied with the Autolite Platinums...