BOSCH 9603 OE Fine Wire Double Iridium Spark Plug - Advanced Original Equipment Technology with 4X Life - Pack of 4

My old plugs were autolite xp iridiums and they had been in for a long time, finally getting about 1`00k miles and due for replacement. My Scion XB 2.4 still started, ran fine, and had no codes. My main concern was that the old plugs would get stuck in the cylinder head, despite using anti seize coating some years ago. The old Autolite XPs came out fine and new Bosch double iridiums were a perfect fit. The old plugs appeared fine, no damage, some central wire wear with a corresponding gap increase. Bosch double iridiums have the hard iridium surface on both the wire surface and the tip and should be more wear resistant than single iridium surface plugs where the center wire will wear off. On starting the engine a smooth idle was apparent but driving revealed that the engine was now more responsive at low rpms and pulled much more smoothly allowing me to shift my manual transmission at low rpm with improved torque. Additionally, on entering the highway I noted that there was no longer a surge when the rpm crossed 3000 rpm, it was smooth, linear and felt stronger. Additionally my factory mpg gauge shows a slight mpg increase. So far I am very happy with the investment in these plugs- 1. Chrome coating on the thread surface means I don't have to worry if I have to ever chance these plugs again, and no anti seize coating is needed. 2. The increase in torque, especially at lower rpms enables me to shift earlier and use less throttle. This increases gas mileage. The old plugs had what I estimate was a .004 inch increase in gap. A more robust spark at low rpms may increase the torque. Or perhaps the 30% advertised decreased voltage required to jump the spark gap allows a hotter spark which causes a better ignition. 3 Bosch guarantees these for 7 years. That's pretty darn good, although the Autolite plugs have a lifetime warranty. In seven years you ought to pull them anyway just to check them.

These were authentic Bosch plugs and was happy to see it wasn’t another china copy. They fit just rite and made a noticeable difference in my turbo lancer as I had auto lite double platinum with the fine tip in there b4 and wasn’t happy with those.

Spark plug quality: I used to buy platinum plugs for their long life. A few years ago I switched to Iridium plugs and really like them. They typically cost less than platinum and seem to have even longer life. These are not re-gapable, so make sure they fit your vehicle. I like Bosch quality overall and when I checked the gaps, I found them to be perfect.

Fit my outback well and works good

Good price.

they work great can tell a difference in them and standard ones

Great spark plugs

2012 2.5 Toyota engine running smooth, exceeding freeway mileage rating in mixed driving, 80000 miles with Carfax reported plug change at 50000 - what difference will replacement spark plugs make? Give it try. $30 and a half hour of work. Old ones were factory spec and visibly but not terribly crusty/worn, so maybe Carfax was wrong about the early replacement by the former owner; still, oem are rated for 100k-120k. Result? Perceptibly smoother engine; 100 lower idle RPM; 1.5 mpg improvement. So yeah, significant improvement. Moral: a good DIY project but if I had been faced with a $300 shop estimate…. Observation: those casual mechanics hanging looking to install basic parts around car parts shops probably do more to keep 7-year + vehicles on the road than dealerships who think in terms of $300-$500-$700 price points.

Works well as it is supposed to do..

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I hadn't replaced the spark plugs in my Toyota Corolla for over 15,000 km and though I should, even though I had no issues. Interestingly I removed the old ones which were identical to these that I just purchased. Obviously I made the right choice again without knowing it. Car continues to run great with 171,000 km.

Excelente cálidad que ofrecen. Hecho en Alemania, coche tiene más potencia y rinde más la gasolina.

Great product. I recommend it and will buy again when necessary.