Engine Oil Additives: Yeah, sure, changing your oil is like the bare minimum. But come on, that’s just scratching the surface. If you’re actually serious about keeping your ride running smooth forever—or, you know, at least until it gives up the ghost—you gotta bring in the heavy hitters. They boost lubrication, fight off nasty sludge, and honestly just help your engine survive the long haul.
In this 2025 guide, we review and compare the best engine oil additives available in the U.S. to help you pick the right product and keep your vehicle running at its best.
Comparison Table – Best Engine Oil Additives 2025
| Product Name | Type | Best For | Key Benefit | Price Range | Buy Link |
| Lucas Heavy Duty Oil Stabilizer | Thickening Stabilizer | High mileage, trucks | Reduces engine wear | $11.95 | Buy on Amazon |
| Liqui Moly MOS2 | Anti-friction | Daily drivers, gas/diesel | Smoother operation | $9.99 | Buy on Amazon |
| Sea Foam Motor Treatment | Cleaner & Stabilizer | Dirty engines, storage use | Cleans and lubricates | $16.50 | Buy on Amazon |
| Bar’s Leaks 1334 One Seal Stop Leak | Friction Modifier | Power stroke & diesel users | Restores lost oil pressure | $5.94 | Buy on Amazon |
| Marvel Mystery Oil | Multi-purpose | Older engines | Cleans and conditions internals | $17.26 | Buy on Amazon |
| STP Oil Treatment | Basic Oil Boost | Budget users | Reduces oil burn and noise | $57.00 | Buy on Amazon |
1. Lucas Heavy Duty Oil Stabilizer
Overview: This stuff’s like muscle for your engine oil—thick, tough, and ready to throw down.
Pros:
✔ Extends oil life
✔ Great for noisy or worn engines
✔ Ideal for trucks and high-mileage vehicles
Cons:
✘ May thicken oil too much in winter
✘ Not ideal for new engines
Best For: Vehicles with 100k+ miles or light diesel use
2. Liqui Moly MOS2 Anti-Friction
Overview: Works for both gas and diesel rides, so your engine runs smoother than a jazz playlist on a rainy night.
Pros:
✔ Reduces friction and engine noise
✔ Improves fuel economy
✔ Long-lasting effects
Cons:
✘ A bit pricey for small bottles
✘ Results may take a few hundred miles
Best For: Commuter vehicles and long-distance drivers
3. Sea Foam Motor Treatment
Overview: Cleans engine internals and stabilizes fuel and oil—perfect for neglected engines or prepping for storage.
Pros:
✔ Dual-use for oil and fuel
✔ Removes varnish, deposits, and sludge
✔ Inexpensive and easy to use
Cons:
✘ Not a long-term treatment
✘ May cause temporary rough idle during cleaning
Best For: Occasional engine detox and seasonal storage
4. Bar’s Leaks 1334 One Seal Stop Leak
Overview: Is a quick and budget-friendly solution designed to seal engine oil leaks caused by dried or shrunken seals and gaskets.
Pros:
✔ Effectively seals minor engine oil leaks
✔ Safe for all types of motor oil
✔ Helps restore flexibility in worn gaskets
Cons:
✘ May not work on larger or mechanical failures
✘ Temporary fix for severe leaks
Best For: Affordable fix without a costly engine repair or teardown.
5. Marvel Mystery Oil
Overview: A historic, budget-friendly additive that cleans engine parts and boosts lubrication.
Pros:
✔ Cleans lifters and injectors
✔ Works with oil or fuel
✔ Budget-friendly multi-use formula
Cons:
✘ Not as strong as modern synthetic formulas
✘ Needs repeated use for results
Best For: Older vehicles with light engine noise
6. STP Oil Treatment
Overview: A basic thick oil additive designed to reduce oil burn and noise in aging engines.
Pros:
✔ Very affordable
✔ Easy to find in stores
✔ Helps with low oil pressure
Cons:
✘ Thick formula can impact flow
✘ Limited long-term impact
Best For: Budget users needing a quick oil boost
Pros & Cons of Using Engine Oil Additives
👍 Pros:
- Improve engine lubrication
- Reduce wear and tear
- Clean engine sludge and varnish
- Extend engine and oil life
- Help older engines run smoother
👎 Cons:
- Not all products suit every engine
- May mask deeper engine issues
- Some thick formulas can impact flow in cold climates
Frequently Asked Questions (FAQs)
Q1. Are engine oil additives safe to use?
A: Yes, most are safe when used as directed. Choose one compatible with your oil type and engine specs.
Q2. Can additives fix engine problems?
A: No. They may improve performance or reduce symptoms, but they cannot fix mechanical damage.
Q3. How often should I use an oil additive?
A: Some additives are fine to use every time you swap your oil.
Q4. Will oil additives void my warranty?
A: You should probably just grab your warranty, squint at the tiny print, and see what it says.
Q5. Can oil additives improve gas mileage?
A: Some of those anti-friction oil additives claim they’ll help you squeeze a bit more mileage out of your gas tank.
Final Thoughts
If you’ve got an older ride or your car’s racked up more miles than your favorite pair of sneakers, engine oil additives are kinda like cheap insurance.Our top pick for versatility is Liqui Moly MOS2, while Archoil AR9100 shines for diesel drivers.
Disclaimer
This post contains affiliate links. If you click and buy through these links, we may earn a small commission at no extra cost to you.
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