AMSOIL Signature Series 5W-50 100% Synthetic Motor Oil
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Maximum Film Strength for High-Performance Engines
AMSOIL Signature Series 5W-50 delivers the thickest protective film in the Signature Series lineup with an HTHS viscosity of 4.45 cP. Built for high-performance and racing-derived engines that demand maximum bearing protection under extreme loads and temperatures.
Key Benefits
- 75% more engine protection against horsepower loss and wear
- Thickest oil film in the Signature Series lineup (HTHS 4.45 cP)
- Guaranteed protection for up to 25,000 miles or 1 year
- Ford WSS-M2C931-C approved for Mustang applications
- GM dexos R approved for Corvette and performance vehicles
- Viscosity index of 185 for consistent protection across temperatures
Technical Specifications
| Property | Value |
|---|---|
| Kinematic Viscosity @ 100°C, cSt | 19.4 |
| Kinematic Viscosity @ 40°C, cSt | 119.5 |
| Viscosity Index | 185 |
| Cold-Crank Viscosity | 5,108 cP (-30°C) |
| HTHS Viscosity, cP | 4.45 |
| Flash Point | 224°C (435°F) |
| Fire Point | 244°C (471°F) |
| Pour Point | -48°C (-54°F) |
| NOACK Volatility, % weight loss | 6.1% |
| Total Base Number (TBN) | 12.5 |
Industry Certifications & OEM Approvals
API
- SP, SN PLUS, SN
Ford
- WSS-M2C931-C (Mustang)
GM
- dexos R
Pros and Cons
Pros
- Industry-Leading Protection: 75% more engine protection against horsepower loss and wear than required by a leading industry standard.
- Extended Drain Intervals: Guaranteed protection for up to 25,000 miles or one year, reducing oil change frequency. Extended drain intervals are safest when supported by an implemented testing program.
- Superior Cold-Start Performance: Flows easily at sub-zero temperatures to reduce engine stress during winter starts.
Cons
- Premium Investment: Higher initial cost compared to conventional or "shelf-brand" synthetic oils.
- Limited Local Retail: Primarily available through authorized dealers and specialized synthetic outlets. National Synthetics is a local stocking dealer. Call 1-678-944-8816 to confirm in-stock items for same-day local pickup.
Get AMSOIL Signature Series 5W-50 100% Synthetic Motor Oil Today
Order directly through Havasu Synthetics for Preferred Customer pricing and fast shipping.
SHOW MY PRICEIndependent AMSOIL Dealer #30576570
Frequently Asked Questions
5W-50 is primarily used in Ford Mustang GT and Shelby models (Ford WSS-M2C931-C), GM Corvette (dexos R), and other high-performance engines. It provides the thickest protective film for maximum bearing protection under extreme loads.
Yes. Despite its heavy 50-weight rating, Signature Series 5W-50 has a pour point of -48°C (-54°F), providing excellent cold-weather flow for year-round use.
Customer Reviews
See all 6,712 reviews5W-50
Product arrived on time as advertised. Quality, ease of pouring and the clear liquid level gauge is a nice feature. The engine seems to like this oil as there is very little engine noise while running.
For Added Protection
Have been running the Signature Series 5W-20 in my son's 2015 F150 with the 5.0 Coyote since we purchased it last year with 148,000 miles. Ran the AMSOIL Engine Flush for 15 minutes before our first oil change with AMSOIL because I want the best protection. Seems to run quieter and hope to get another 150K miles, running all fluids on AMSOIL... Signature Series Engine Oil, Signature ATF, Severe Gear for Differentials, Signature ATF for Transfer Case, P.I. Performance Improver every 4K miles, Upper Cylinder Lubricant, Dominator Coolant Boost
Best fully synthetic made
I’m running a 2019 Sierra with the 6.2L. My truck isn’t in the recall range, but I still want to have the best oil in it. And my employer pays for my oil changes. I don’t like what I’m reading about the manufacturer’s reasons for using 0W-20/40 in these engines (gas mileage). So I’m using a thicker oil. I’m seeing zero difference in mileage since I switched to this oil, which is good.
My review
I’ve just recently started a job as a medical courier. I was unaware of the amount of miles that I would be putting on my truck. I’ve used AMSOIL in the past but now realize that I need the best oil $$ can buy to care for my truck. Every thing I’ve read about AMSOIL from independent testing says that they are the best and truly a full synthetic oil. Pennsoil ultimate would be second. All the rest Mobil 1, Castro and valvoline are just marketing.
Great product
Best oil on the market will use in all my vehicles and equipment
Great Oil
Our 2008 Toyota Highlander has over 227000 miles on it and still does not need to have oil added between oil changes. Never run any other oil from when we bought the car with 9000 miles on it.
GREAT PRODUCTS
Always get great products at great and fair prices, good delivery time as well.
Best in class
I’ve been using Amsoil for 2 decades and never had a engine failure.
When nothing but the best is called for.
After viewing numerous reviews comparing motor oils on YouTube. I came to the conclusion that 0W-40 Amsoil Signature was, without a doubt, the best. When you are protecting a twin turbo engine, nothing else is better than Amsoil 0W-40. Nothing.
Best oil ever. Been using them since I was 16.
This oil is literally the best oil ever. My Toyota now has 430,815 miles on it and still going strong. I love amsoil will never in my life use any other brand I even run it in my lawn mower and dirt bikes. Keep up the great work and excellent top tier oil products. Thank you guys. I’ve been using amsoil for over 20 years now.
Quality product
Best oil you can buy. I used it many years ago. I’m back as a customer. I didn’t like not being able to buy it in a store when I needed it. I will say their delivery service is fast and good. Not a problem getting oil.
300,000+ Ford F-150
Installed this oil in my F-150 Ecoboost @5,000 miles and have more than 300,000 +miles on it and will never use anything else
Change out mobile One to AMSOIL
After reviewing and reading information about AMSOIL, Changed out Mobile One to AMSOIL in my TOYOTA. I've been using AMSOIL in my commerical lawn mowers for a couple of years and pleased with quality of protection. Thanks
No other product
Have used email in Ram 1500 since purchased new in 2017. Have done the research on Amsoil and other synthetic products, have prices of mind that the Amsoil product is providing the best lubricators for my truck. Have also expanded to using in my jeep wranglers after I did rebuild on both of their engines. Will continue to use into the future.
Oil change
Had my oil changed and the technicians told the guy at the front desk, This guy uses the good stuff.
BEST OIL EVER
Better oil by far than the Mobil 1, Castrol , etc.
My experience with Amsoil products
I have been using Amsoil products for well over 25 years. During that time I have had many different vehicles of all brands that I have used Amsoil in the crankcase, transmission, rear end and transfer cases. all have been good vehicles with no problems at all with lubricated parts. The 2 I am most proud of though are the 2 Dodge Dakotas I owned that I put over 280,000 miles on and only changed the oil and filter every 20.000 miles. Also maintained the other lubricated areas at 50,000 mile intervals and both still ran as strong as when I bought them new! You just can not go wrong with the Amsoil brand of products for ALL your cars or trucks needs.
Overpriced
Your product have become overpriced and shipping prices are out of control, can't imagine if I wasn't A preferred paying customer...
My Legacy
I have been using Amsoil since 1979. I started as a dealer while in the Air Traffic Control Acadamy. I maintain between 4 and 8 vehicles routinely [currently 7] and I would not have time for the routine maintenance if it was not for Amsoil. Amsoil is the best oil and by, far the best, oil filter in the industy. My twin sons just became 16 years old. For their birthday I taught them how to change oil in their vehicles using Amsoil. I am passing down the tradition of using Amsoil as my legacy to them. It is the best advice that I can give them.
Great product but broken bottle
I feel like my engine noise has been quieter the last 1000 miles. Definitely less vibrations. However, when I opened the package one of the bottles was broken. So I had to run to a store and grab another one. I always stick with and oil. Everything was perfect except I was half a quart short since I had a bottle break. Hasn’t happened prior so maybe it was a one time thing
They say it's the best
They say that Amsoil is as good as it gets. I keep buying it. Amsoil products have never disappointed me. I like my vehicles to be paid for. I like to be able to keep them active and dependable. I enjoy the relationship I feel to a vehicle that people associate with me. It seems like Amsoil has helped me keep all of my vehicles more years than average. That's what I want.
Diesel oil
The oil is going on 3000 miles and hasn't lost a drop.
GMC So far so good non scientific
2008 4X4 GMC Sierra 6.0 VortecMax. 129,000 miles I’ve only use this oil since first oil change. Truck was delivered with 4 miles. No engine problems. Change interval I used was 6 months or 5,000 miles.
Good motor oil
Very good motor oil. Have been using Amsoil for over 15 years. I use it in my off-road vehicles, my truck, suv and lawn equipment. I change my signature Amsoil at 15,000 kms, well before it’s time, but I prefer more often oil changes. I would give it 5 stars if price was lower. Otherwise, two thumbs up for this great product.
Independent AMSOIL Dealer #30576570. Product information sourced from AMSOIL. Visit AMSOIL.com for the most current product details and availability.