
Originally Posted by
Mile2
Already tried both copper and iridium., Iridium does not translate to high fuel efficiency but on performance, if you use your car on mostly on city driving it is better to use Copper and have it replaced every 10K-20K Kms., if you use your car mostly on highways use iridium and replaced them every 40K-60K Kms.
But since, my ride was on LPG most of the time, I have also tried one step colder plugs which is Denso IKH22. in terms of performance this is so far my best choice.