The SparkPlugCross Blog
Plain-English guides to spark plugs: diagnosis, replacement, gapping, cross-referencing and brand comparisons.
7 Symptoms of Bad Spark Plugs — and What They Mean
Rough idle, misfires, hard starts, poor fuel economy — the seven most common signs your spark plugs are worn out, and what each one is telling you.
When Should You Replace Your Spark Plugs?
Replacement intervals for copper, platinum, double-platinum, iridium and ruthenium spark plugs — and why the metal decides how long they last.
How to Gap a Spark Plug Correctly
A simple step-by-step on checking and setting spark plug gap with a feeler gauge, why gap matters, and how to avoid damaging the electrode.
Can You Use a Different Brand of Spark Plug?
Yes — if it matches fit and heat range. Here is exactly what has to line up to safely cross from NGK to Denso, Champion, Bosch, Autolite and back.
Reading a Spark Plug: What the Tip Color Tells You
A used spark plug is a diagnostic readout. Tan, black, oily, white, melted — here is what each color and condition says about your engine.
NGK vs Denso vs Autolite: How the Brands Compare
The big spark plug brands compared on technology, OE fitment and value — and why the right answer is usually "whichever makes the correct plug for your engine."