Types of Spark Plugs: Which One Your Engine Needs
Spark plugs differ by tip metal, and the metal affects how the plug wears; this guide matches iridium and platinum plugs to your engine.
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A rough idle and a hard start often point at the same small part. Types of spark plugs differ by the metal on the tip, and that metal affects how the plug wears and how long it lasts. This guide covers the plug types, how to match a plug to your engine, and the plugs for a home garage.
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| # | Product | Shop Score | Buy |
|---|---|---|---|
| 1 |  NGK LKR7DIX-11S Iridium IX Spark Plug | 9.7/10 | Buy on Amazon |
| 2 |  ACDelco 41-962 Professional Platinum Spark Plug | 9.6/10 | Buy on Amazon |
| 3 |  NGK # 3186 G-Power Platinum Spark Plugs TR5GP | 9.6/10 | Buy on Amazon |
NGK LKR7DIX-11S Iridium IX Spark Plug
An NGK Iridium IX spark plug, LKR7DIX-11S, in a 4 pack, with a 0.6mm iridium center and a 40,000 to 50,000 mile typical life.
Pros
- 0.6mm iridium center for a consistent spark
- 40,000 to 50,000 mile typical life
- Triple gasket seal stops gas leakage
- Trivalent plating resists corrosion and seizing
Cons
- Warranty term is not stated
- 4 pack only, no 8 pack stated
- No heat range figure is stated
- Insulator length is stated without a figure
ACDelco 41-962 Professional Platinum Spark Plug
An ACDelco 41-962 Professional Platinum spark plug in a set of 8, with a double platinum point pad and a pure copper core.
Pros
- Double platinum point pad, center and ground
- Pure copper core for cooler electrode temperature
- One-piece fired-in suppressor seal
- 8 plugs in the set
Cons
- No warranty is stated
- No hex size is stated
- No tip diameter is stated
- No resistor value is stated
NGK # 3186 G-Power Platinum Spark Plugs TR5GP
An NGK G-Power Platinum spark plug, TR5GP, with a wider heat range than ordinary plugs and a triple gasket seal.
Pros
- Wider heat range than ordinary plugs
- Resists carbon buildup and pre-ignition
- Triple gasket sealing process
- Cross-references many part numbers
Cons
- Pack count contradiction: title says 8 pieces, spec table says 1 item
- Warranty term is not stated
- No hex size is stated
- No tip diameter is stated
Types of Spark Plugs
A spark plug lights the fuel mix in the cylinder, and the tip metal sets the plug apart. The plugs in this guide use iridium or platinum on the tip, with a copper core inside the ACDelco plug. The NGK Iridium IX listing states an ultra-fine 0.6mm iridium center for a strong, consistent spark, and a 40,000 to 50,000 mile typical life.
The platinum plugs here state their own strengths: the NGK G-Power listing states a wider heat range than ordinary plugs, and the ACDelco listing states a double platinum point pad on the center and ground electrode for durability. Both listings state a seal: a triple gasket seal against combustion gas leakage on the NGK plugs, and a fired-in suppressor seal for a gas-tight seal on the ACDelco plug.
How to Pick the Right Spark Plug
Match the plug to the engine, not to the shelf. Check the manual for the plug the engine calls for, then match the part number: the NGK Iridium IX here is LKR7DIX-11S, the NGK G-Power is TR5GP, and the ACDelco is 41-962. The hex size matters for the socket: the NGK Iridium IX listing states a 5/8 inch hex, and our guide to spark plug socket sizes covers the socket side.
Mind the pack count as well as the part number. The NGK Iridium IX comes in a 4 pack and the ACDelco in a set of 8, while the NGK G-Power title says 8 pieces and its spec table says 1 item, so confirm the count before ordering.
Types of Spark Plugs: Picks for the Garage
Each plug below covers a step in the pick above: the part number, the tip metal and the pack count, so match the plug to the engine before ordering.
Use rated jack stands on solid ground, wear eye protection with power and air tools, keep fuel-burning equipment out of a closed garage, and follow the manual for every tool. Read our Safety Disclaimer.
The wrong plug for an engine can foul or overheat, so check the manual for the plug the engine calls for before you order.
Before You Start: What to Check
- Confirm the part number. Match LKR7DIX-11S, TR5GP or 41-962 to the manual.
- Check the hex size. The NGK Iridium IX listing states a 5/8 inch hex.
- Confirm the pack count. The NGK G-Power title says 8 pieces while its spec table says 1 item.
- Mind the tip metal. Iridium and platinum plugs state different wear claims; pick the plug the manual calls for.
- Check the warranty wording. Both NGK listings state only that a manufacturer warranty is included, with no term stated.
FAQ: garage tools
What are the types of spark plugs?
The plugs here sort by tip metal: iridium on the NGK Iridium IX, with a 0.6mm center, and platinum on the NGK G-Power and the ACDelco 41-962. The ACDelco plug also states a pure copper core inside.
How long do iridium spark plugs last?
The NGK Iridium IX title states a 40,000 to 50,000 mile typical life. That figure is the maker’s stated life for the plug, not a promise for every engine, so check the manual for the change interval your engine calls for.
How do I know which spark plug fits my engine?
Check the manual for the plug the engine calls for, then match the part number: LKR7DIX-11S, TR5GP or 41-962. The hex size matters for the socket as well, and the NGK Iridium IX listing states a 5/8 inch hex.
Do these spark plugs come with a warranty?
Both NGK listings state only that a manufacturer warranty is included, with no term stated. The ACDelco listing states no warranty at all, so the term is not stated anywhere here.
Related: spark plug socket sizes, spark plug problems, thread repair kit for spark plugs and our engine and shop equipment hub.
