Spark plugs aren’t made to last forever. Even ones tipped with iridium will wear out over so many miles traveled, and those are the longest lasting spark plugs. The good thing about spark plugs is they can easily be changed out when they become worn or damaged. So what kind of plugs do you use when it comes time to replace them? Most automotive experts will agree that OEM spark plugs are superior to cheap aftermarket replacements, and here’s why.
The Many Problems Associated with Cheap Plugs
The truth about aftermarket VW spark plugs is that they are made to be as inexpensive as possible. Parts suppliers in the aftermarket industry assume, or at least hope, that you can’t tell a good spark plug from a bad one, and they aim to take advantage of this ignorance by using cheap materials and manufacturing processes.
However, cheap is bad when it comes to spark plugs because:
Spark Plug Material Quality is Vital: One of the main reasons that many aftermarket spark plugs cost less than OEM plugs is the use of lower grade materials. Most OEM plugs, for example, are made with high purity platinum-iridium alloy coated tips, nickel-coated threads for corrosion resistance, and strong ceramic insulators. Aftermarket plugs often a lesser grade iridium platinum alloy (or even just platinum), which reduces the lifespan of the plugs. Aftermarket plug manufacturers will omit the nickel plating on the plug threads as well, even though doing so increases the risk of a plug seizing inside the cylinder head when it’s time to replace the plug. Lower cost ceramic insulators are used by after-market plug manufacturers as well, even thought they are often more fragile. Etc. Etc.
Exact Resistance Matters A Lot: Every spark plug has what’s known as an “interference suppression resistor”, which ensures the electrical noise created by the firing spark plug doesn’t interfere with the rest of the electrical system. If this resistor is substandard, the plugs will can cause all sorts of problems, from the innocuous (radio static or Navigation system problems) to the serious (malfunctioning engine sensors, ABS sensors, etc.).
Aftermarket Plug Fitment Isn’t Always Consistent: If spark plugs are even the tiniest bit longer or shorter than OEM specifications, or if the electrode gap is even the slightest bit off, this can rob your engine of both power and fuel economy.
Electrode Design and Shape is Essential: OEM spark plugs have carefully crafted electrodes that are ground into a specific shape — this process is costly and adds complexity and time to manufacturing. This shape is important to optimize performance and efficiency of the plug. If you change to an aftermarket blade and point design, you’ll lose fuel economy and horsepower.
The Hidden Cost of Cheap Plugs
Where’s the hidden cost? At the pump! Even if you aren’t necessarily concerned with how long a plug lasts in your engine, the quality of the interference suppression resistor, etc., a cheap set of spark plugs will lower your gas mileage. An inferior set of plugs for your Volkswagen can cost you an extra $25-50 a year in gas, depending on how much you drive and how much fuel costs. Multiply that amount over a period of years and you find that “cheap” spark plugs are actually pretty darn expensive.
Bottom line, spark plugs are not where you want to cut corners for the sake of saving money. OEM Volkswagen spark plugs optimize performance and fuel economy — saving you on your biggest vehicle expense (fuel) after a simple service.