Double platinum
Specifically built for modern waste-spark ignition systems. Durability is their strong suit.
"Waste-spark ignition system is where two spark plugs fire simultaneously through a single coil. During the process, one spark ignites the fuel-air mixture on the compression stroke, while the other fires during the exhaust stroke when no ignition is needed," Rubia explained.
Iridium
These are the gold standard and are known to last up to 200,000 kilometres. Both mechanics concur that the iridium plugs offer better throttle response and improve the fuel efficiency of the engine.
"If you want to future-proof your car, iridium plugs are the way to go," notes Peter Odhiambo, an electrical mechanic at Madaraka Auto Clinic in Nairobi.
Silver
A niche choice, used mainly in performance cars, high-revving engines, and motorcycles, thanks to their superior thermal conductivity. The silver plugs are renowned for their excellent thermal conductivity, as they transfer heat away from the firing tip more efficiently than other materials.
"You can find the silver plugs mostly fitted in Porsche Cayennes and Subarus for petrolheads. However, they wear out very fast since silver is a soft metal," says Odhiambo.
Getting the right plug
Different manufacturers design ignition systems around specific plug types; hence, it is crucial to follow recommendations.
"Downgrading from iridium to copper in a modern engine is asking for trouble. You'll see misfires, poor acceleration, and even damage to ignition coils," Mwangagi warned.
On the other hand, upgrading to long-life plugs, such as iridium, in a car that originally used copper can be a smart move for drivers who want reliability with less frequent servicing.
When to change plugs
Spark plugs also have an expiry date, for lack of a better word. Below are some of the signs that your plugs are worn out and need to be replaced.
Misfires are causing the car to jerk while driving. Hesitation or sluggishness when accelerating or overtaking.
Rough idling
If you are visiting the pump stations more frequently than before.
All three mechanics engaged by The Standard agree that a timely change is one of the cheapest ways to avoid expensive engine repairs. "Spark plugs are the heart of combustion in the engine block. Treat them well, and your engine will reward you every time you turn the key," Rubia summed up.
Without spark plugs, there's no fire, no motion, no drive. Though tiny, they remain vital for performance and reliability.
Choosing the right type and replacing them on schedule can mean the difference between smooth, efficient motoring and costly garage visits.