What To Spray In Spark Plug Hole – Step-by-Step

What To Spray In Spark Plug Hole

Spark plug holes can collect a lot of debris and oily substances, which affect its performance. So, cleaning and handling spark plug holes shouldn’t be overlooked at all. This is where many drivers face the common issue of deciding what to spray in spark plug hole.

If you’re experiencing this dilemma, don’t worry, you’re not alone in this one, nor are you the first one to face it. There are a number of do’s and don’ts when it comes to spraying substances in a spark plug hole. We will be going through it one by one to assist you in this vehicle maintenance.

Without further chit-chat, let’s dive right into the details. 

What to Spray in Spark Plug Hole?

Depending on what you intend to do with the spark plug, there are a variety of car products that you can spray into its slot.

Here are the materials that have the green light to be used on a spark plug hole –

1. WD-40

To prevent rust build-up, it’s best to use WD-40 in spark plug hole. The WD-40 does this by making a protective barrier around the hole to repel moisture. It also doubles as a lubricant, as using a small amount can help you pull the spark plug out of an already rust-jammed hole.

2. Carburetor Cleaner

Ask any auto tech about the best spark plug hole cleaner, and they’ll tell you to use a carb cleaner. Carburetor cleaners are much stronger than WD-40s and can effectively break down hardened gunk and debris for easy removal.

3. Air Gun

Don’t know how to get debris out of spark plug hole quickly? Compressed air inside a can or an air gun is the best for instant results. It’s recommended that after using a carb cleaner or WD40, an air gun should be used to take out the excess debris.

For thorough cleaning, an air gun should be used before spraying any cleaning formulas into the spark plug hole. This ensures that the loose materials surrounding the spark plug are removed to make way for the WD-40 or carb cleaner.

4. Oil

A tiny amount of oil can be used on spark plugs to ease it out of its hole. If you need a lubricant for a rusted over spark plug hole, a small teaspoon amount of oil or less would be more than enough for the job.

However, you will have to be mindful about how much you’re using so that the spark plug does not become too much loose.

5. Brake Cleaner

Using a brake cleaner in spark plug hole will quickly dissolve any oil and gunk build-up. You can use a wire brush to scrub off the debris from not just the spark plug and its hole but also from the threads. Afterward, go over it with an Emery cloth to remove any carbon residue.


Can I spray starting fluid in the spark plug hole?

Yes, you can spray starting fluid into the bore of your car engine’s spark plug. There is also an intake located close to the air filter of your engine, which can also be sprayed with the starting fluid.

What should not be sprayed in a spark plug hole?

Sand, dust, moisture, and gunk should be nowhere near the bore of your spark plug. As for products to avoid using, we recommend not using anything other than WD-40, carb cleaners, brake cleaners, and oil on the spark plug hole.

Is it OK to spray carb cleaner in a spark plug hole?

Yes, carb cleaners are safe to use for spark plug holes as long as they are used carefully and in moderation. They can dissolve hardened materials effectively and work better than regular WD-40s.

How to get debris out of the spark plug hole?

First, clear out any loose debris surrounding the bore of your spark plug with compressed air/an air gun.

Then, use a carb cleaner or WD-40 to clean out the hardened debris.

After that, you can use a vacuum or the air gun again to get rid of any residue.


There’s never any clear-cut answer for what to spray in spark plug hole or how to do it, so hope that we helped with clearing all the confusion surrounding the topic. 

Remember to go through the cleaning process as carefully as you can, and use the products in small amounts. To stay extra safe, have the spark plug looked at by an auto tech to know exactly which product will be best for your engine’s spark plug.

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