I've always replaced my spark plugs every 100,000 km (62,500 miles), and tend to use Motorcraft/Autolite platinums on the Mercury and NGK Iridiums on the Mitsubishi. On the Mitsu, I also replace the ignition wires, distributor cap and rotor whilst I'm at it.
Yesterday, I replaced the plugs and the coolant pump on my cousin's '07 TrailBlazer. Mileage was just shy of 161,000 km (100,625 miles) and the originals were still on the car, albeit not in the best shape.
The initial complaint was rough idle, black smoke out the tailpipe when the gas was released and a slight vibration at speeds over 110 km/h (70 MPH). Buddy of mine has a GM Tech-II, which he used to inspect the truck, and it turned out there was a firing problem with cylinders 3 and 4.
When I pulled out the plugs, they had hard carbon deposits on them (nothing excessive) and the tip wasn't exactly the best shape. Although I didn't measure it, the gap seemed bigger than it should have been. Ended up replacing them with the same ACDelco plugs that came on the car and the issue went away. Also cleaned the MAF sensor and throttle body, which was quite filthy, as well as flush the coolant with fresh G-05.
Anyhow, this got me questioning how the quality of gasoline affects spark plug life. I'm a religious user of MMO in the Merc and TC-W3 in the Mitsu, and when the plugs come out, there are no carbon deposits on them, just a goldish tint. The electrodes have some normal wear to them, but not too much of a difference when compared to the new ones. The plugs on the TrialBlazer, on the other hand, were worn, with some hard carbon deposits on them. The electrode also looked worn down.
I realize some people do not like fuel additives, but both MMO and TC-W3 have done very well for me. Whilst I realize this isn't a very fair comparison, I was questioning myself as to whether or not I would be able to get 160,000 km (100,000 miles) out of my plugs, which is the recommended replacement interval. I'm not too certain on the composition of our gasoline, but I know it's high sulfur (500 ppm). No clue on detergency.
Yesterday, I replaced the plugs and the coolant pump on my cousin's '07 TrailBlazer. Mileage was just shy of 161,000 km (100,625 miles) and the originals were still on the car, albeit not in the best shape.
The initial complaint was rough idle, black smoke out the tailpipe when the gas was released and a slight vibration at speeds over 110 km/h (70 MPH). Buddy of mine has a GM Tech-II, which he used to inspect the truck, and it turned out there was a firing problem with cylinders 3 and 4.
When I pulled out the plugs, they had hard carbon deposits on them (nothing excessive) and the tip wasn't exactly the best shape. Although I didn't measure it, the gap seemed bigger than it should have been. Ended up replacing them with the same ACDelco plugs that came on the car and the issue went away. Also cleaned the MAF sensor and throttle body, which was quite filthy, as well as flush the coolant with fresh G-05.
Anyhow, this got me questioning how the quality of gasoline affects spark plug life. I'm a religious user of MMO in the Merc and TC-W3 in the Mitsu, and when the plugs come out, there are no carbon deposits on them, just a goldish tint. The electrodes have some normal wear to them, but not too much of a difference when compared to the new ones. The plugs on the TrialBlazer, on the other hand, were worn, with some hard carbon deposits on them. The electrode also looked worn down.
I realize some people do not like fuel additives, but both MMO and TC-W3 have done very well for me. Whilst I realize this isn't a very fair comparison, I was questioning myself as to whether or not I would be able to get 160,000 km (100,000 miles) out of my plugs, which is the recommended replacement interval. I'm not too certain on the composition of our gasoline, but I know it's high sulfur (500 ppm). No clue on detergency.
