Are you thinking about buying Original Equipment Manufacturer (OEM) or factory approved spark plugs for your car? Think again. You could get a better set of spark plugs for your car at half the asking price!
Car manufacturers do not always recommend the best possible plugs when you take your car in for servicing. Sadly, economic factors often rule the day and at times, OEM plugs are just sufficient and nothing more.
While that might be alright for some, you could spend the same amount of money for a set of superior grade plugs. These better plugs are boxed in the manufacturer’s own packaging rather than the vehicle manufacturer’s packing.
What’s more, most vehicle manufacturers in the world procure plugs from global manufacturers like NGK, Denso, Bosch, Champion, Brisk and KLG to mention a few.
Using a spark plug manufacturer’s application catalog will help you decide on the right spark plug for your car engine, usually at lesser cost.
There are a few types of upgraded plugs, but the most common are single iridium and double iridium spark plugs. The one’s pictured below are from Denso.
The double version gives the best burn velocity and requires the least energy to jump the gap and it lasts longer. The single type is better suited for force induction engines, as they are more robust.
Both types of plugs reduce idle misfire, especially the double iridium plugs. It is fantastic at solving lean burn misfire in some direct injection engines, which typically run ultra lean air-fuel ratios to save fuel,
These stratified charged lean burn designs require precise gas flow patterns to gather a rich mixture at the plug’s tip to initiate ignition and spread to the outer periphery’s homogeneous lean mixture. This is fine when the engine is new.
However, with high mileage direct injection engines, more soot builds up intake ports. This spoils the precise air flow pattern to achieve stratified fuel mixture and consequently causes misfire every few cycles.
The double iridium electrode helps mitigate this by improving ignitability, thus improving idle quality, fuel consumption and more importantly, throttle response.
A test on an unstable idling Alfa Romeo JTS engine showed improved idle quality by at least 70%. Some of the improvement was attributed to a set of new oxygen sensors on the car, as aged sensors have slower switching speeds that cause less precise mixture control.
We suggest that you research and decide against OEM spark plugs and try to use a better one, especially since it is sold at a lower price.
Many official service centre will intimidate the less informed of engine damage if they use non OEM spark plugs. But if you get the correct reach, size, heat range and cross-referencing to the manufacturer’s application catalogue, you’ll be good to go.
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