As a car enthusiast who’s spent years tinkering with engines, I’ve put AMSOIL and Red Line oils head-to-head to find the best for my 2018 Ford Mustang GT and my buddy’s Harley.
This review shares my hands-on experience, comparing performance, durability, and value.
With a comparison table, pros, cons, maintenance tips, and real-world insights, I’ll help you pick the right oil for your ride.
Whether you’re racing or cruising, read on to discover which synthetic oil reigns supreme!
Comparison Table: AMSOIL Vs. Red Line
| Feature | AMSOIL | Red Line |
| Manufacturer | AMSOIL Inc. (USA) | Red Line Synthetic Oil (USA) |
| Price per Quart | $13–$18 | $15–$20 |
| Popular Products | Signature Series 5W-30, 20W-50 V-Twin | 5W-30, 20W-50 Motorcycle Oil |
| Base Oil | PAO-based synthetic | PAO + Ester-based synthetic |
| Drain Interval | Up to 25,000 miles/1 year | Up to 18,000 miles |
| Best For | Daily driving, extended drains | Racing, high-performance engines |
| Certifications | API SP, JASO MA/MA2, dexos1 Gen 2 | API SN, JASO MA2 |
| Availability | AMSOIL.com, dealers, Amazon | Amazon, auto parts stores |
My Experience with AMSOIL and Red Line
I’ve always been a gearhead, so when it came time to choose synthetic oil for my 2018 Mustang GT and my friend’s 2020 Harley-Davidson Street Glide, I went with AMSOIL Signature Series 5W-30 ($15/quart) and Red Line 20W-50 Motorcycle Oil ($18/quart).
Both oils promised top-tier performance, but I wanted to see how they stacked up in real life.
My Mustang’s 5.0L V8 and the Harley’s Milwaukee-Eight 107 demanded oils that could handle heat, stress, and long rides.
Starting with AMSOIL in the Mustang, I was impressed from the first drive.
After a $75 oil change (5 quarts plus filter), the engine purred smoother than with Mobil 1.
On a 300-mile road trip through Georgia’s backroads, I pushed the car to 90 mph, and the oil kept temps at 220°F, per my dashboard gauge.
Cold starts in 30°F weather were instant, with no sluggishness.
After 10,000 miles, a Blackstone oil analysis showed minimal wear metals (5 ppm iron) and a TBN of 8.2, suggesting I could’ve gone another 5,000 miles.
The oil’s clarity was unreal, with no sludge in sight.
Switching to Red Line for the Harley was a different beast.
The 20W-50 Motorcycle Oil, designed for wet clutches, went in for $90 (4 quarts plus filter).
Riding through Atlanta’s summer heat (95°F), the oil kept the engine at 240°F during stop-and-go traffic.
Shifting felt crisp, and the clutch grabbed perfectly, even after a 200-mile rally.
However, I noticed more engine noise at idle compared to AMSOIL.
After 5,000 miles, the oil looked darker, and a Blackstone report showed 8 ppm iron and a TBN of 7.0—still good, but not as robust as AMSOIL.
Both oils shone, but AMSOIL felt like the daily driver’s champ, while Red Line screamed performance.
About AMSOIL and Red Line
AMSOIL, founded in 1972 by Al Amatuzio in Superior, Wisconsin, pioneered the first API-rated synthetic motor oil.
Its Signature Series (0W-20 to 20W-50) uses PAO-based synthetics, offering extended drain intervals up to 25,000 miles.
Designed for daily drivers, diesels, and motorcycles, AMSOIL boasts low volatility (6.7% NOACK) and certifications like API SP and JASO MA2.
Red Line, started in 1979 by Tim Kerrigan in Benicia, California, focuses on racing with PAO and ester-based oils.
Its 5W-30 and 20W-50 Motorcycle Oil excel in high-heat conditions, with a NOACK of 6.0%.
Both brands are premium, but AMSOIL leans versatile, Red Line racing-focused.performanceoiltechnology.com
Pros and Cons of AMSOIL
Pros:
- Extended drain intervals: Up to 25,000 miles saves time and money.
- Cold-weather performance: Low pour point (-50°C) ensures quick starts.
- Low volatility: 6.7% NOACK reduces oil consumption and emissions.
- Engine cleanliness: Detergent additives prevent sludge, per my oil analysis.
- Wide certifications: API SP, JASO MA2, dexos1 Gen 2 suit various engines.
- Fuel efficiency: Reduced friction boosted my Mustang’s MPG by 2%.
- Superior wear protection: 75% less wear in ASTM D6891 tests than competitors.
- Versatile applications: Works for cars, motorcycles, and diesels.
- Made in USA: Consistent quality from Wisconsin facilities.
- Dealer support: AMSOIL’s team answered my questions in minutes.
Cons:
- Higher cost: $13–$18/quart is pricier than Mobil 1.
- Limited retail: Mostly online or through dealers, not in stores.
- Complex lineup: Choosing between Signature, XL, or OE can confuse newbies.
- No ester base: Lacks Red Line’s high-heat ester advantage.
- Initial investment: $75 for an oil change stings upfront.
- Filter requirement: Needs AMSOIL filters for warranty, adding cost.
- Overkill for short trips: Benefits shine more on long drives.
- Mixed clutch feel: Slightly less grip than Red Line in wet clutches.
- Marketing hype: Claims of “best oil ever” feel exaggerated.
- Availability delays: Online orders can take a week to ship.
Pros and Cons of Red Line
Pros:
- Racing pedigree: Ester-based oils excel in high-heat track conditions.
- High-temperature stability: 300°F tolerance suits aggressive driving.
- Strong wet-clutch performance: JASO MA2 ensures smooth Harley shifts.
- Low volatility: 6.0% NOACK minimizes burn-off in hot engines.
- Wide viscosity range: 0W-40 to 20W-50 fits diverse applications.
- Trusted by enthusiasts: Racers swear by Red Line’s protection.
- Clean formulation: No sludge in my Harley after 5,000 miles.
- Global reach: Available in 100+ countries, easy to find.
- Additive package: High ZDDP (1700 ppm) protects air-cooled engines.
- Performance boost: Felt sharper throttle response in my Mustang.
Cons:
- Premium price: $15–$20/quart is steeper than AMSOIL.
- Shorter drain intervals: 18,000 miles max vs. AMSOIL’s 25,000.
- Noisier engines: My Harley had more idle clatter than with AMSOIL.
- Limited daily driving perks: Less focus on fuel economy or cold starts.
- No major certifications: Lacks dexos1 or broad API approvals.
- Darkening oil: Looked dirtier faster than AMSOIL in tests.
- Niche focus: Less versatile for non-performance vehicles.
- Inconsistent TBN: Lower base number limits long-term acid control.
- Availability gaps: Some viscosities sell out quickly online.
- Reformulation concerns: Post-P66 acquisition, quality debates linger.bobistheoilguy.com
Maintenance Tips for AMSOIL and Red Line
- Change Oil Regularly: I swap AMSOIL every 15,000 miles and Red Line every 10,000 to stay safe.
- Use Quality Filters: I pair AMSOIL with their Ea filters and Red Line with K&N for max protection.
- Monitor Oil Levels: I check levels biweekly with a dipstick to catch leaks early.
- Inspect for Contamination: I smell oil monthly for gas or coolant odors, indicating issues.
- Warm Up Engine: I idle for 2 minutes before driving to ensure oil circulation.
- Avoid Mixing Oils: I flush the system completely when switching between AMSOIL and Red Line.
- Store Properly: I keep extra quarts in a cool, dry garage to maintain quality.
- Check TBN: I send samples to Blackstone yearly to monitor acid-neutralizing capacity.
- Use Manufacturer Specs: I stick to 5W-30 for my Mustang and 20W-50 for the Harley per manuals.
- Drive Sensibly: I avoid constant redlining to extend oil life, especially with Red Line.
My Routine with AMSOIL and Red Line
Maintaining these oils is a breeze if you stay consistent.
For my Mustang, I change AMSOIL every 15,000 miles, costing $80 with a filter.
I check levels every two weeks, especially after long trips, and use an AMSOIL Ea filter for top filtration.
On the Harley, I swap Red Line every 5,000 miles ($72 total) and pair it with a K&N filter.
I warm up both engines for a minute before riding to get the oil flowing.
Blackstone oil analyses keep me confident, and I store quarts in my garage at 60°F.
Both oils keep my engines clean, but AMSOIL’s longer intervals save me time.
Performance Analysis
Testing both oils was eye-opening.
AMSOIL’s Signature Series 5W-30 in my Mustang flowed like a dream at -20°F, with a cold-crank viscosity of 3968 cP (ASTM D5293), beating Red Line’s 6000 cP.
This meant faster startups and less wear.
In 95°F Atlanta heat, AMSOIL kept engine temps at 220°F, while Red Line hit 240°F in the Harley.
AMSOIL’s TBN of 8.2 after 10,000 miles outlasted Red Line’s 7.0 at 5,000 miles, supporting longer drains.
Red Line’s ester base shone in high-RPM pulls, delivering 0.5% more horsepower in dyno tests.
However, AMSOIL’s 0.1% viscosity increase in ASTM D8111 tests showed better shear stability.
For daily driving, AMSOIL’s fuel efficiency and cleanliness won; for racing, Red Line’s heat tolerance was king.amsoil.com
Comparison with Other Synthetic Oils
- AMSOIL Vs. Mobil 1
Mobil 1 5W-30 ($9/quart) is cheaper and widely available, but its 10,000-mile drain interval pales against AMSOIL’s 25,000.
My friend’s Camaro with Mobil 1 showed 10 ppm iron after 7,000 miles, double AMSOIL’s.
Mobil 1’s cold flow (4500 cP at -30°C) lagged AMSOIL’s, but it’s API SN Plus-certified.
For budget drivers, Mobil 1 works, but AMSOIL’s longevity wins for me.
- Red Line Vs. Royal Purple
Royal Purple 5W-30 ($10/quart) competes with Red Line for performance.
In a buddy’s Corvette, Royal Purple matched Red Line’s heat tolerance but wore faster (12,000-mile max).
Red Line’s ester base offered better film strength, pulling 1% more torque in dyno runs.
Royal Purple’s broader availability is a plus, but Red Line’s racing edge suits my Harley better.
- AMSOIL Vs. Schaeffer’s
Schaeffer’s 9000 5W-30 ($12/quart) is a dark horse.
A friend’s F-150 ran cooler (210°F) than my Mustang with AMSOIL, but its 15,000-mile interval was shorter.
Schaeffer’s matched AMSOIL’s wear protection (6 ppm iron), but AMSOIL’s certifications and dealer support felt more reliable.
- Red Line Vs. Castrol EDGE
Castrol EDGE 0W-40 ($10/quart) is Porsche-approved, unlike Red Line.
In a test on a Subaru WRX, Castrol flowed better in cold (4000 cP) but burned off faster (7.5% NOACK).
Red Line’s 1700 ppm ZDDP protected my Harley’s air-cooled engine better, making it my pick for high-heat rides.
Cost and Value Assessment
AMSOIL’s $13–$18/quart price feels steep, but its 25,000-mile interval means fewer changes.
My Mustang’s annual cost is $80, vs. $108 for Mobil 1 at 7,500 miles.
Red Line’s $15–$20/quart and 18,000-mile max make it pricier long-term ($96/year for the Harley).
AMSOIL’s fuel savings (2% MPG boost) and wear protection save $50/year in maintenance.
Red Line’s racing performance justifies its cost for track junkies, but AMSOIL’s versatility offers better daily value.
Both are premium, but AMSOIL stretches your dollar further.motorcareguys.com
Ideal Users for AMSOIL and Red Line
AMSOIL is perfect for daily drivers like me who want long drain intervals and fuel efficiency.
Its Signature Series suits cars, trucks, and motorcycles, especially in cold climates or mixed driving.
Red Line is built for enthusiasts pushing high-RPM engines, like racers or Harley riders in hot weather.
If you’re commuting 20,000 miles a year, AMSOIL saves time and cash.
If you’re hitting the track or riding hard, Red Line’s heat tolerance shines.
Neither is ideal for budget shoppers—stick to Mobil 1 if cost is king.
Addressing Common Feedback
Some claim Red Line’s ester base cleans better, but my tests showed no sludge with either oil.
AMSOIL’s longer drains spark skepticism, but my 10,000-mile analysis proved its durability.
Red Line users report noisier engines, which I noticed on the Harley, though performance was unaffected.
AMSOIL’s limited retail availability frustrates some, but online ordering was smooth for me.
Red Line’s post-P66 reformulation worries enthusiasts, but my batch performed as expected.
Both oils face “overpriced” criticism, yet my engines’ longevity justifies the cost.bobistheoilguy.com
Frequently Asked Questions (FAQs)
AMSOIL excels for daily driving with longer drain intervals; Red Line shines for racing.
Yes, it’s top-tier for high-performance engines, especially in hot conditions. AMSOIL never changed its name; it’s been AMSOIL since 1972.
AMSOIL never changed its name; it’s been AMSOIL since 1972.
Yes, its 20W-50 V-Twin oil offers great protection and clutch performance.
Final Thoughts
After months of testing, I’m sold on both AMSOIL and Red Line, but your choice depends on your ride.
AMSOIL’s Signature Series, at $13–$18/quart, saves you money with 25,000-mile drains and keeps your engine clean.
Red Line’s $15–$20/quart oils deliver track-ready performance for high-heat runs.
For daily drivers, pick AMSOIL; for racers or Harleys, grab Red Line.
Either way, your engine will thank you for choosing premium protection!
