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AMSOIL Synthetic 20W/50 High Performance Diesel & Gasoline Oil (ARO)

SAE 20W-50 Synthetic High Performance Motor Oil
Formulated for use in both gasoline and diesel engines. Offers multi-functionality and excellent wear protection. Ideal for applications where the extra protection of a higher viscosity oil is desired. Ecellent for motor homes and older vehicles, as well as most types of modern equipment. Performance specific
ations include:

API SL, CF & CI-4+


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Package sizes include:


1-Quart Bottle
1-Quart Bottles (case of 12)
1-Gallon Bottle
1-Gallon Bottles (case of 4)
16-Gallon Keg
30-Gallon Drum
55-Gallon Drum


Download Color product data sheet for AMSOIL ARO 20W50

AMSOIL High Performance Synthetic 20W-50 Motor Oil is specially formulated to provide superior protection and performance in the most demanding applications. It provides a wide range of protection in all four-cycle gasoline and diesel engines, including pickups, RVs, cars and off-highway vehicles and is ideal for use in high-stress vehicles subject to stop-and-go driving, short trips, high temperatures, frequent trailer pulling and off-road use.

Download Color product data sheet for AMSOIL ARO 20W50

Resists High Temperature Vaporization
Conventional motor oils tend to "boil off" in high temperatures, losing up to 25 percent of their original weight. These vaporized oils circulate poorly, reduce fuel efficiency and contribute to excessive emissions and engine wear. AMSOIL High Performance Synthetic 20W-50 Motor Oil resists vaporization. In fact, according to the NOACK Volatility Test, which measures the weight loss of an oil due to evaporation, AMSOIL Synthetic 20W-50 only loses 6.0 percent of its weight in high temperature service, surpassing rigorous European standards set at 13 percent weight loss in high temperature testing. The superior vaporization resistance of AMSOIL Synthetic 20W-50 keeps engine wear, oil consumption and emissions to a minimum, while keeping oil circulation efficient and fuel economy high.

Resists Oxidation and Thermal Breakdown
Conventional oils oxidize in high operating temperatures, producing sludge and deposit build-up that contribute to corrosion, increased engine wear and decreased fuel economy. AMSOIL High Performance Synthetic 20W-50 Motor Oil resists oil breakdown, maintaining its cooling and lubricating properties and providing extended drain intervals. It continues to provide maximum protection at temperatures that oxidize conventional oils. The advanced heat transfer capabilities and high lubricity of AMSOIL 20W-50 Motor Oil keep engines running in their optimum temperature range for top performance and long life.

Provides High Shear Stability
AMSOIL Synthetic 20W-50 Motor Oil surpasses the North American SAE and European ACEA oil specifications for high temperature/high shear (HTHS) viscosity. It retains its viscosity at temperatures and loads that cause conventional oils to shear back to a lower viscosity. AMSOIL 20W-50 Motor Oil maintains an extremely protective viscosity of 4.9 cP at 302°F (150°C) in the ASTM D 4683 High Temperature/High Shear Test, significantly exceeding test limits.

Provides Low Temperature Protection
AMSOIL Synthetic 20W-50 Motor Oil maintains outstanding low temperature fluidity, ensuring easy engine cranking for quick starts. During sub-zero temperatures, it flows to all parts of the engine much quicker than conventional petroleum 20W-50 oils, greatly reducing the rate of wear and increasing engine life.

Resists Deposit Formation
AMSOIL Synthetic 20W-50 Motor Oil is highly resistant to oxidation, running significantly cleaner than conventional motor oils. AMSOIL 20W-50 has a superior detergent/dispersant additive package that, when tested after tens of thousands of miles of use in the crankcase, still exhibits outstanding deposit control.

Inhibits Rust and Corrosion
AMSOIL Synthetic 20W-50 Motor Oil contains special rust and corrosion inhibitors to protect iron parts, as well as copper, lead and aluminum bearing materials.

Provides Extended Drain Intervals
AMSOIL Synthetic 20W-50 Motor Oil features a superior synthetic composition and advanced performance additives, performing much longer than competing conventional and synthetic oils.

AMSOIL High Performance Synthetic 20W-50 Motor Oil may be used in gasoline or diesel engines requiring oils meeting the following specifications.

  • API SL/CF & CI-4+
  • ACEA A3, 83, E2, E3, E5
  • Chrysler MS 8809A
  • Cummins CES 20071, 20072, 20076, 20077
  • Ford ESR M2C 179A
  • Daimler Chrysler 228.3, 229.1
  • Mack EO-L, EO-M, EO-M+
  • Volvo VDS, VDS-2
  • Allison C-3, C-4
  • Caterpillar TO-2, TO-3

AMSOIL High Performance Synthetic 20W-50 Motor Oil is compatible with conventional petroleum oils; however, mixing AMSOIL 20W-50 with a conventional oil will shorten the drain period of AMSOIL 20W-50. Engine oil additives or after-market products are not recommended for use with AMSOIL 20W-50.

In personal cars and light-duty trucks with nonturbocharged gasoline engines, change oil at three times the engine manufacturer's recommended drain interval or one year, whichever comes first.

In turbocharged gasoline engines, change oil at two times the engine manufacturer's recommended drain interval or six months, whichever comes first.

In high-performance and racing engines, change oil at intervals specified by used oil analysis.

In light-duty and nonturbocharged diesel engines, change oil at two or more times the engine manufacturer's recommended drain intervals if the findings of used oil analysis support those drain intervals or six months, whichever comes first.

In heavy-duty and turbocharged diesel engines, change oil at two or more times the engine manufacturer's recommended drain intervals if the findings of used oil analysis support those drain intervals or six months, whichever comes first.

In marine craft and occasionally used gasoline engines, change oil at three times the engine manufacturer's recommended drain interval or one year, whichever comes first.

In fleet vehicles and industrial gasoline engines, change oil at two times the engine manufacturer's recommended drain interval or six months, whichever comes first.

If the vehicle is equipped with an AMSOIL Oil Filter, the filter should be changed at 12,500-mile or six-month intervals (whichever comes first) in gasoline engines and 7000-mile or six-month intervals (whichever comes first) in diesel engines. Non-AMSOIL oil filters should be changed at the engine manufacturer's recommended filter change interval.




AMSOIL Synthetic 10W-30/SAE 30 Heavy Duty Diesel Oil (ACD)

Kinematic Viscosity @ 100°C, cSt (ASTM D-445)


Kinematic Viscosity @ 40°C, cSt (ASTM D-445)


Viscosity Index (ASTM D-2270)


Cold Crank Simulator Apparent Viscosity @ -25°C, cP
(ASTM D-2602)

Pour Point °C (°F) (ASTM D 97)

-38 (-35)

Flash Point °C (°F) (ASTM D 92)

236 (457)

High Temperature/High Shear @ 150°C and 1.0 X 106 s-1, cP (ASTM D 4683), cP


Noack Volatility, % weight loss (g/100g) (ASTM D-5800)


Four Ball Wear Test (ASTM D 4172 @ 40 kgf,
150°C, 1800 rpm, 1 hour, Scar in mm)



Total Base Number


Unsurpassed Diesel Engine Protection

Diesel engine emissions have been an ongoing environmental concern for the past few decades, and the United States, Europe and Japan have responded to demands to reduce harmful particulates and nitrogen oxides (NOx). In the U.S., particulate and NOx levels were first regulated in 1988, with regulations becoming increasingly stringent through the years. In fact, 1988 standards set NOx and particulate levels at 14.4 g/kWhr (grams/kilowatts – hour) and 0.8 g/kW-hr respectively, while 2010 standards have been set at 0.27 g/kW-hr and 0.013 g/kW-hr respectively. By 2010, diesel engines will be considered “clean,” but getting there will require sulfur-free fuel, improved in-cylinder combustion, exhaust after-treatment, vehicle design changes and diesel oils that are compatible with after-treatment systems.

Between the years 1988 and 1991, emission standards were met by improving in-cylinder combustion through the use of unit injectors, electronic controls, controlled air swirl, improved combustion bowl design, reduced piston crevice volume, turbo-charging, air inter-cooling and reductions in oil consumption.

The year 1991 also saw the use of high top rings to lower particulate emissions. By 1998, retarded fuel injection timing was introduced to meet increasingly stringent NOx emission standards. High top rings and retarded fuel injection timing increased soot loading on the oil, leading to the introduction of API diesel oil category CH-4 in order to prevent viscosity increases and increased wear due to soot.

In order to meet 2002 emission standards, most engine manufacturers introduced exhaust gas recirculation (EGR) engines, which recirculate a portion of the exhaust to the engine’s combustion chamber, lowering peak combustion temperature. Although EGR engines effectively reduce emissions, they also run hotter and introduce higher levels of soot and acid into the oil, leading to increased wear, increased oil viscosity and shorter oil drain intervals.

The API CI-4 diesel oil specification was introduced in December 2001 to protect against the higher temperatures and increased levels of acids, soot and oxidation associated with EGR engines, while some manufacturers released their own diesel oil performance specifications in order to assure optimum protection for their equipment. Mack released its stringent EO-N Premium Plus High Performance Diesel Engine Oil specification in the spring of 2002, then upgraded it to EO-N Premium Plus 03 in April 2003 due to soot-related oil thickening and shear that occurred after a certain length of highway time.

API issued an upgrade to its CI-4 specification, CI-4 PLUS, in September 2004 in order to provide improved oxidation resistance, shear stability, acid neutralization and soot dispersancy for EGR engines. CI-4 PLUS certified diesel oils also meet most of the individual manufacturer issued specifications and are backward compatible with older diesel oil specifications and engines. CI-4 PLUS oils must first meet the original requirements of CI-4, with the additional requirements of passing the 90-Pass Shear Stability Bench Test and the Mack T-11 engine test, a more stringent upgrade of the Mack T-8E soot-viscosity test required for CI-4.

In order to meet 2007 particulate standards, exhaust after-treatment devices such as particulate filters (DPF’s) and continuously regenerative traps (CRT’s) will be incorporated into diesel engines, creating new challenges for diesel oils. AMSOIL Synthetic Diesel Oils are ahead of the curve and ready to meet the challenges of tomorrow.

AMSOIL Synthetic Diesel Oils surpass the most stringent modern diesel oil specifications, including CI-4 PLUS and EO-N Premium Plus 03. Formulated with top-of-the-line synthetic base stocks and advanced additive packages, AMSOIL Synthetic Diesel Oils effectively control the increased soot and acid levels associated with EGR units, while remaining shear stable at high temperatures, avoiding the damaging sludge and deposit build-up that contribute to decreased fuel efficiency, corrosion and accelerated engine wear. The drain intervals of AMSOIL diesel oils may be extended by oil analysis in EGR-equipped engines.

Emission control technology has increased soot loading of diesel oils, prompting original equipment manufacturers to shorten drain interval recommendations. Even at increased soot levels, AMSOIL Synthetic Diesel Oils continue to offer outstanding wear protection. Soot and iron wear levels were measured over 900 hours of operation in a 2002 EGR-equipped Mack LE613-Rear Loader running AMSOIL 15W-40 Synthetic Heavy Duty Diesel and Marine Motor Oil. As seen in the graph, even at increased soot levels, the rate of engine wear remained well below the Mack condemnation limit of 0.5 parts per million per hour (ppm/h).


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