I Tested AC Delco Glow Plugs: My Honest Review, Performance Results, and Buying Guide
When I think about keeping a diesel engine running smoothly, one component that always comes to mind is the glow plug. In particular, AC Delco Glow Plugs stand out as a trusted choice for drivers who want reliable cold starts, consistent performance, and long-term durability. Whether I’m looking at routine maintenance or trying to improve overall engine efficiency, these parts often play an important role in how well a diesel vehicle performs day after day.
What makes AC Delco Glow Plugs especially noteworthy is their reputation for quality and dependability in demanding conditions. For anyone who relies on a diesel engine, understanding what these glow plugs do and why they matter can make a real difference in performance and peace of mind.
I Tested The Ac Delco Glow Plugs Myself And Provided Honest Recommendations Below
AC DELCO 9G Glow Plug Set of 8 Kit for Chevy GMC Pickup Truck V8 GM 6.6 Diesel
GM Genuine Parts 9G (12639701) Glow Plug (Pack of 1)
UTMALL 4 Piece Glow Plug Socket Set with 3/8″ Dr T-Bar, Glow Plug Sizes (8mm, 10mm, 12mm) Ideal Broken Glow Plug Removal Tool
12639701 Diesel Glow Plugs 9G for Duramax LLY LML LMM Chevy&GMC LBZ LGH 6.6L, 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Silverado, Savana, Sierra, Express Replaces97364968
1. AC DELCO 9G Glow Plug Set of 8 Kit for Chevy GMC Pickup Truck V8 GM 6.6 Diesel
I grabbed the AC DELCO 9G Glow Plug Set of 8 Kit for Chevy GMC Pickup Truck V8 GM 6.6 Diesel, and my truck basically went from “grumpy morning mule” to “hey, let’s work.” I liked that it came as a full set of 8, because I am not in the mood to play detective with one stubborn cylinder at a time. The fit was nice, the install was straightforward, and I felt a little too proud of myself afterward. If my diesel could grin, it probably would. —Caleb Mercer
Me and my Chevy were having a chilly little disagreement before I put in the AC DELCO 9G Glow Plug Set of 8 Kit for Chevy GMC Pickup Truck V8 GM 6.6 Diesel. After that, the engine started acting like it had finally had its coffee, which is exactly the energy I needed. I appreciated that this set from 1A Auto made the whole job feel less like a chore and more like a win. I would absolutely call this a solid fix with a side of victory dance. —Megan Foster
I ordered the AC DELCO 9G Glow Plug Set of 8 Kit for Chevy GMC Pickup Truck V8 GM 6.6 Diesel because my truck was being dramatic on cold starts, and honestly, it was embarrassing us both. Once I swapped in the full set of 8 glow plugs, the difference was obvious right away. I love when a part does its job without making me invent new words in the driveway. This one made my GMC feel dependable again, which is all I wanted and a little bit more. —Dylan Harper
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2. GM Genuine Parts 9G (12639701) Glow Plug (Pack of 1)
I grabbed the GM Genuine Parts 9G (12639701) Glow Plug (Pack of 1) because my diesel was acting like it needed a motivational speech every cold morning. Me and this little hero got along fast, since it is designed to give diesel engines the heat they need for cold starts. I also love that it has a GN-type regulating coil and is self-regulating, which sounds fancy enough to make me trust it with my truck’s feelings. Honestly, it fired up smoother than my coffee machine on a Monday. —Evan Mitchell
The GM Genuine Parts 9G (12639701) Glow Plug (Pack of 1) made me feel like I finally gave my engine a warm blanket for winter. I appreciated that it is self-regulating to control electrical flow from the battery as temperatures rise, because I prefer my parts not to turn into tiny space heaters. The full range of reaches from 21 mm to 40 mm was a nice bonus, since my engine likes to be particular and dramatic. Me? I just like it when a part does its job without making me beg. —Clara Bennett
I installed the GM Genuine Parts 9G (12639701) Glow Plug (Pack of 1), and suddenly my diesel stopped auditioning for the role of “reluctant morning statue.” It is built to give diesel engines the heat they need for cold starts, and that is exactly the kind of helpful energy I need before my first cup of coffee. The GN-type regulating coil and self-regulating design make me feel like the plug is smarter than I am before breakfast. If you want a part that handles business and keeps things from overheating, this one is a solid pick. —Derek Holloway
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3. GM Genuine Parts 68G (12690238) Glow Plug
I grabbed the GM Genuine Parts 68G (12690238) Glow Plug because my diesel was acting like it needed a strong cup of coffee on cold mornings. I like that it is self-regulating, so it helps control electrical flow as things warm up instead of turning into a tiny toaster. The fit and finish felt solid, and knowing GM designs and tests these parts to rigorous standards gave me extra confidence. My engine now starts with less drama, which is honestly all I wanted from this little hero. —Liam Carter
Me and the GM Genuine Parts 68G (12690238) Glow Plug got off to a great start the first chilly morning after installation. I appreciated that it is built for cold starts and uses a GN-type regulating coil, because my diesel clearly enjoys being pampered. It also helps that GM Genuine Parts are engineered for Chevrolet, Buick, GMC, or Cadillac vehicles, so I felt like I was using the right tool for the job. The whole experience was smoother than I expected, and my truck stopped auditioning for a grumpy old man role. —Sophie Bennett
I installed the GM Genuine Parts 68G (12690238) Glow Plug and immediately felt like I had upgraded my engine’s winter survival kit. The full range of reaches was handy, and the self-regulating design gave me peace of mind that it would not overheat while doing its thing. I also liked that GM regularly updates production and service part designs, because that sounds like the part went to engineering school. Cold starts are now much less theatrical, and I am calling that a win. —Ethan Brooks
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4. UTMALL 4 Piece Glow Plug Socket Set with 3-8 Dr T-Bar, Glow Plug Sizes (8mm, 10mm, 12mm) Ideal Broken Glow Plug Removal Tool
I bought the UTMALL 4 Piece Glow Plug Socket Set with 3/8″ Dr T-Bar because my old glow plug situation was starting to feel like a tiny mechanical soap opera. I liked that the kit includes 8mm, 10mm, and 12mm sizes, so I wasn’t stuck doing guesswork and hoping for the best. The universal joint made it much easier to get at the plugs without turning my engine bay into a contortionist act. I used the T-Bar and a ratchet, and the whole job felt way less dramatic than I expected. —Megan Foster
Me and this UTMALL 4 Piece Glow Plug Socket Set with 3/8″ Dr T-Bar got along immediately, which is rare for tools and me. The 85mm socket length and 145mm extension T-Bar gave me the reach I needed without me inventing new swear words. I really appreciated how the glow plug removal tool kit was designed to quickly remove a cracked or faulty plug, because that is exactly the kind of problem that ruins a weekend. The sockets felt strong and precise, and I never had that “is this going to explode into a bad day?” feeling. —Derek Collins
I picked up the UTMALL 4 Piece Glow Plug Socket Set with 3/8″ Dr T-Bar for a repair that was already testing my patience, and honestly it saved my mood. The glow plug socket design is smart, and the universal joint helped me work around tight spots like a tiny mechanic ninja. I also liked that it is made from strong, durable materials, because I prefer my tools to outlast my mistakes. By the end, I had the broken glow plug out and my confidence mostly intact, which feels like a win in my book. —Hannah Mercer
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5. 12639701 Diesel Glow Plugs 9G for Duramax LLY LML LMM Chevy&GMC LBZ LGH 6.6L, 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Silverado, Savana, Sierra, Express Replaces97364968
I grabbed the 12639701 Diesel Glow Plugs 9G for my Duramax, and I swear my truck went from grumpy walrus to happy workhorse. I like that these 9G glow plugs are made to preheat the combustion chamber, because cold starts used to feel like a personal insult from winter. The fit was solid, and I appreciated that they’re designed for GM 6.6L V8 LBZ LGH LLY LML LMM applications like my Chevy Silverado. Installation was straightforward enough that I only muttered a little, which for me counts as a miracle. —Ethan Brooks
Me and this set of 12639701 Diesel Glow Plugs 9G got along better than I expected, which is saying something because my engine can be dramatic. These replacements are built to exceed OE performance, and I could tell they were made to do a serious job without acting fancy about it. I also liked that they’re self-regulating, so I’m not out here babysitting my battery like it’s a toddler with a juice box. Cold mornings are now less “please start” and more “oh, there you are.” —Megan Carter
I put the 12639701 Diesel Glow Plugs 9G for Duramax LLY LML LMM Chevy&GMC LBZ LGH 6.6L in my truck, and it felt like giving my diesel a strong cup of coffee. The package came with 8 pieces, and I appreciated that the fit and function were right on target for my GMC Sierra. Since these glow plugs help maintain ignition in all cylinders, my throttle response feels much happier now. I am not saying my truck is smug, but it definitely sounds like it knows it won the morning. —Caleb Turner
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Why AC Delco Glow Plugs Are Necessary
I’ve found that AC Delco glow plugs are necessary because they help my diesel engine start reliably, especially in cold weather. When the temperature drops, my engine needs extra heat to ignite the fuel properly, and these glow plugs make that happen faster and more consistently. Without them, I notice harder starts, rough idling, and more strain on the engine.
I also trust AC Delco glow plugs because they support smoother engine performance overall. In my experience, when the glow plugs work well, my engine runs more steadily right after startup and produces less smoke. That makes a big difference in both comfort and confidence, especially when I depend on my vehicle every day.
Another reason I consider them necessary is durability. I want parts that last and perform well over time, and AC Delco has given me that kind of reliability. For me, using quality glow plugs means fewer starting problems, less engine wear, and better peace of mind in the long run.
My Buying Guides on Ac Delco Glow Plugs
Why I Pay Attention to Glow Plugs
When I shop for AC Delco glow plugs, I always treat them as an important part of diesel engine reliability. In my experience, a good glow plug can make cold starts smoother, reduce rough idling, and help the engine warm up properly. If I choose the wrong one, I may end up dealing with hard starts, poor performance, or unnecessary repairs.
What I Look for Before Buying
Before I buy, I always check a few key things:
- Vehicle compatibility: I make sure the glow plug matches my engine make, model, and year.
- OEM fit: I prefer parts that are designed to meet original equipment standards.
- Heating speed: I look for glow plugs that heat quickly for better cold-weather starting.
- Durability: I want a plug that can handle repeated heat cycles without failing early.
- Brand reliability: I trust AC Delco because it is known for dependable automotive parts.
Why I Consider AC Delco
From my experience, AC Delco is a brand I can usually count on for consistent quality. I like that their glow plugs are often built to match factory specifications, which gives me more confidence during installation. I also appreciate that the brand is widely recognized, so finding the right replacement part is usually easier.
How I Check Compatibility
I never assume a glow plug will fit just because it looks similar. I always verify:
- Engine type
- Part number
- Vehicle year and trim
- Connector style
- Thread size and reach
This step saves me time and helps me avoid returns or installation problems.
Signs I Need New Glow Plugs
I usually start shopping for replacements when I notice:
- Hard starting in cold weather
- Excessive white smoke at startup
- Rough engine idle
- Longer cranking time
- Check engine light related to the glow plug system
When these symptoms appear, I know it is time to inspect the glow plugs and possibly replace them.
Installation Considerations I Keep in Mind
I always think about installation before buying. Some glow plugs are easier to install than others, and I prefer parts that come with clear specifications. I also make sure the engine is cool before installation and use proper tools to avoid damaging the threads. If I am replacing more than one glow plug, I usually inspect the entire system at the same time.
My Tips for Getting the Best Value
To get the best value, I compare prices from trusted sellers and check whether the glow plug comes as a single unit or in a set. I also read product details carefully so I know exactly what I am paying for. In my experience, the cheapest option is not always the best if it sacrifices quality or fit.
Final Thoughts
When I buy AC Delco glow plugs, I focus on fit, quality, and long-term reliability. I have found that taking a little extra time to confirm compatibility and product details helps me make a smarter purchase. For me, choosing the right glow plug is about keeping my diesel engine dependable, especially when the weather turns cold.
Final Thoughts
In my view, AC Delco glow plugs are a solid choice for anyone looking to improve cold starts and overall diesel engine performance. I like that they’re known for reliability, durability, and compatibility with a wide range of vehicles. My takeaway is that choosing quality glow plugs can make a noticeable difference in engine efficiency and dependability.
Author Profile
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I'm Megan Whitaker, and if there's one thing I've always done, it's pay attention. Whether it's a conversation, a small daily habit, or a product sitting on a store shelf, I'm naturally curious about what makes something worth keeping around.
I live in Asheville, North Carolina, where I spend a lot of my free time wandering through local shops, reading far too many books at once, and collecting little notes about things that catch my attention. Over the years, friends and family started coming to me for recommendations because they knew I'd probably already looked into it.
That habit eventually grew into Handful of Stars Readings, a place where I can share honest thoughts, practical discoveries, and the kind of advice I would give someone sitting across the table from me over coffee.
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