Some non-conventional Toyota platinum spark plugs only have platinum on both the center electrode and on the ground electrode (that’s why they’re called “Double Platinum”). This design reduces wear while providing a long service life of 60,000 miles. If you take a close look at Genuine Toyota Double Platinum Spark Plugs, you’ll notice that the center electrode has a raised design compared to some non-conventional Toyota single platinum spark plugs. The raised design provides excellent ignitability for a strong spark…translating into a smooth idle and strong performance. Also, some non-conventional Toyota platinum spark plugs rely solely on platinum; Toyota adds nickel and iridium to the platinum. This alloy helps make the spark plug strong and durable, while helping to prevent cracking.
In today’s world of high performance automobiles, not all engines are created equal, and neither are spark plugs. That’s why Toyota created these special Iridium Spark Plugs to meet the needs of high-performance engines (available for select Toyota models). These spark plugs feature a smaller center electrode, which translates into higher performance and meet platinum spark plug replacement intervals of 60,000 miles. Iridium is a more durable material than platinum (its melting point is approximately 1,200° F higher than platinum).
Select Toyota models feature the Toyota Direct Ignition System (DIS). Introduced in 1994, this system created a more efficient and cost effective engine for Toyota owners. It’s also more demanding on spark plugs. With this system, spark plugs fire twice as often — accordingly, a 30,000 mile non-conventional Toyota spark plug may only last 15,000 miles (that means twice as many tune-ups). Toyota created a special dual ground electrode spark plug that delivers optimum performance and durability for DIS-equipped Toyotas. Genuine Toyota U-Groove Spark Plugs For Toyota engines that require conventional spark plugs, we offer Genuine Toyota U-Groove Spark Plugs. Instead of a rectangular ground electrode, U-Groove Spark Plugs feature a special groove in the middle of the ground electrode (hence the name “U-Groove”). With this design, when the spark plug is fired, the U-Groove traps the gas and then produces a
Information source: Toyota parts and service materials for customers