Thanks for the reply. I ordered a set of the BKR8EIX plugs off of Amazon this morning.Welcome to the forum 888 and congrats on the new Cruze!
J is absolutely right with one exception. While we were talking I forgot to mention that the one area the 8's have an advantage over the 7's is smoothness under load at VERY low RPM, like below 900 RPM. Above 1000 RPM they both work much better than the OE Iridium plugs, but if you lug the engine down to the lowest of RPM the 8's are a bit smoother. Even with the Eco`s extra tall 6th gear I can lug it down to 26-27 MPH before it protests enough to warrant a downshift. I would get about 29-30 MPH out of the 7`s, and the OE Iridiums (even gapped properly) needed to be shifted before about 33-34 MPH. With the stock plugs I was convinced the cam timing changed below 1100 RPM and the engine just wouldn't make any torque that low. A plug upgrade showed me otherwise.
The real impressive difference is how much easier it is to get the car off the line. With either plug you can walk the car from a dead stop with very little throttle, where the stock plugs require much more throttle and higher RPM to get the same response.
I'd be interested in an update from prince_bigd as he's an aggressive driver and is also using the BKR8EIX. A colder plug will foul easier under load and he's one of our test rats. If his plugs are still going strong I'd recommend them. I'm an easy driver and much less likely to foul plugs.
Welcome to the club!
Amazon.com: 4 New NGK Iridium IX Spark plug BKR8EIX # 2668: Automotive
$28 doesn't seem like much of an investment if it helps the car drive better how I drive it, which is about like you drive it. I'm not in a big hurry to get anywhere and if a car seems quick and responsive when I want it to be, that's fine by me. I'm not a 9/10 type of driver. This is my first new car in 11 years and I'm not inclined to beat on it.
I assume the car will have a learning period after the plug change when the ECU responds and adjusts everything? How long does that take?
I had an early S-10 that ran great every time I would adjust the timing but went back to running like crap in a few miles as the ECU took over and made it stupid again. I eventually found a TSB on the web for an ECU issue, back then you could swap the EEPROM chips and after I did that, it was a lot better. As good as a base model S-10 could be, anyway.