190K on Original Plugs?

Finally got around to pulling the plugs on my 2008 V6, 4x4 Double Cab. Picked it up last fall with 186K. Had most of the maintenance records but didn't find anything on the plugs being changed. Pulled out NGK on drivers side and Denso on passenger, original I assume. Hard to tell from the pic but the Denso plugs were in noticeably better condition, both the center and side electrode were less deteriorated. The gap was obviously way off on all, too wide for my gauge to check. Other than the occasional slow start it ran good, although it was a bit of a pooch.

Replaced with 6 Denso plugs gapped at 0.040. Had been tracking my mileage on Fuelly since I got it. Ran close to 20 mpg avg through the fall and was 16-18 this winter. Overall on 4600 miles was 17.9 MPG. First tank on the new plugs, 18.1 MPG..

 

That's amazing.

 

Actually averaging 17.9 MPG on those things is pretty amazing.

 

I bet it was kind of hard to get the wires off, right?

 

Well you beat my record; when I bought my '99 I changed the air filter and the plugs in it just out of habit, to start fresh. It had 169k on it at that point, and I was more than a little surprised when I pulled out 3 NGK's and 3 Denso's.

So after I found that out it got new coils, new wires, new fuel filter, a coolant flush, and new gear oil in the transmission and diffs. I figured if the PO hadn't changed the plugs he hadn't changed anything else either, lol.

 

I thought the fuel filters were lifetime and never needed changing? Or is that only 2nd gens and up?

 

It is (or at least it's not a maintenance item)

But a '99 is a first gen.

 

Why didn't you go back with the Denso/NGK mix?

There's lots of Siennas and Highlanders out there with big miles on original plugs, because the rear bank is quite challenging to get to. Not uncommon to be quoted $300 or so for a plug change.

 

I thought you were the OP. Realized later you were talking about a 99.

I still don't trust the "lifetime" filter thing though lol.

Not understanding the argument. Tacomas have OEM copper plugs. Why would you want a short lifespan plug?

The plugs aren't that hard to get to. Takes like 1 hour to change for a novice, 30 mins for a tech with experience. But it you wanted to avoid changing the plugs, go iridium. They last like 3 times as long as copper plugs.

Plus I thought the Highlanders had irridium plugs, not copper like the Tacomas.

 

This thread is proof that driving style is probably the biggest factor in MPG's.

My 2013 couldn't pull those numbers on new plugs. But that is a direct result of my abnormally heavy right foot.