AMSOIL'S Original Premium Protection 10W40
SAE 10W-40 Synthetic Premium Protection Motor Oil (AMO)
This was the original product Al Amatuzio first formulated in 1972 but has continuously been advanced with the best additives available for your classic or high performance vehicle.
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. Excellent for motor homes and older vehicles, as well as most types of modern equipment. Also compatible for use in motorcycles.

Heavily fortified with zinc/phosphorus anti-wear additives for maximum protection.
Provides extra anti-wear protection required by engines with flat tappets and high tension valve springs.
Ideal for high mileage vehicles
Applications include street rods, cars, trucks, motorcycles, RVs, marine, tractors, heavy equipment and other applications where this oil is appropriate.
You can also order in our new AMSOIL Online Store
See the special AMSOIL service bulletin on all AMSOIL high Zinc products.
- API SL, SJ, SH... (Gasoline)
- API CI-4+, CH-4, CF (Diesel)
- JASO MA, ISO-L-EMA (Wet Clutch)
PRODUCT DESCRIPTION
AMSOIL Synthetic 10W-40 Premium Protection Motor Oil is specially formulated to provide superior protection and performance in a wide variety of demanding applications. By incorporating high quality synthetic base stocks and additives, AMSOIL Premium Protection Oil exceeds the needs of large and small gasoline or diesel engines in cars, motorcycles, trucks, motor homes, maintenance equipment, heavy equipment, street rods and marine applications. AMSOIL Premium Protection Oil resists oxidation, neutralizes acids, inhibits corrosion, reduces wear and protects against deposits. It is ideal for high mileage vehicles and high-stress vehicles subject to hot temperatures, heavy hauling, trailer pulling or off road use. AMSOIL Synthetic 10W-40 Premium Protection Motor Oil provides flexibility and performance beyond conventional oils for convenience and trouble free operation.
AMSOIL, the leader in automotive synthetic lubrication, produced the world’s first API qualified synthetic motor oil in 1972. Trust the extensive experience of AMSOIL The First in Synthetics® to do the best job protecting your engine.
Provides Superior Wear Protection
AMSOIL Synthetic 10W-40 Premium Protection Motor Oil is a high viscosity oil engineered to protect against metal-to-metal contact. It resists viscosity shear and is formulated with a heavy treatment of anti-wear additives for excellent protection of gears, bearings, cam lobes and other high-pressure components in engines and transmissions. AMSOIL Premium Protection Synthetic Motor Oil helps extend engine life.
Exceeds the Requirements of Wet Clutch Transmissions
AMSOIL Premium Protection Synthetic Motor Oil contains no friction modifiers, making it ideal for motorcycles, maintenance equipment and other wet clutch transmission applications. Formulated to prevent clutch glazing and slippage, it insures smooth clutch engagement and long term, dependable transmission operation. AMSOIL Synthetic 10W-40 Motor Oil reduces clutch wear for extended transmission life.
Resists Oxidation and High Temperature Breakdown
AMSOIL Premium Protection Synthetic Motor Oil overcomes the thermal deficiencies common to conventional petroleum oils. Volatilization (burn-off), oxidation and excessive deposit formation from high heat are greatly reduced. Viscosity thickening is controlled and engines run clean, promoting cooler operation and long engine life in air or liquid cooled engines.
Extends Drain Intervals in Gasoline and Diesel Engines
The superior AMSOIL synthetic base stock and additive technology exceeds the requirements of both gasoline and diesel engines. AMSOIL Premium Protection Motor Oil neutralizes acids, disperses soot and lasts longer in service than conventional oils.
You can also order in our new AMSOIL Online Store
MIXING AMSOIL
AMSOIL Synthetic 10W-40 Premium Protection Motor Oil is compatible with conventional and synthetic motor oils. Mixing AMSOIL motor oils with other oils, however, will shorten the oil life expectancy and reduce the performance benefits. AMSOIL does not support extended drain intervals where oils have been mixed. Aftermarket oil additives are not recommended for use with AMSOIL Synthetic Oils.
SERVICE LIFE
AMSOIL Synthetic 10W-40 Premium Protection Motor Oil is recommended for use up to 15,000 miles or one year, whichever comes first, in unmodified(1), mechanically sound(2) automotive gasoline or diesel engines. In motorcycles, small engines, stationary engines, heavy equipment and other applications, extend drain intervals based on oil analysis or follow the manufacturer recommended drain interval.
AMSOIL Ea™ full-flow oil filters are designed for extended drain intervals. They stop smaller particles, flow more oil and last longer than regular filters. For best performance, use AMSOIL Ea™ full-flow oil filters and replace at the time of oil change. Other oil filters should be changed at standard OEM* intervals.
*OEM - Original Equipment Manufacturer
(1) Engines operating under modified conditions are excluded from extended drain recommendations. Examples include the use of performance computer chips; non-OEM approved exhaust, fuel or air induction systems; and the use of fuels other than those recommended
for normal operation by the manufacturer.
(2) Mechanically sound engines are in good working condition and do not, for example, leak oil or consume excessive amounts, are not worn out, do not overheat, do not leak anti-freeze and have properly working emission control systems. AMSOIL recommends repairing malfunctioning engines prior to the installation of AMSOIL synthetic oils.
HEALTH & SAFETY
This product is not expected to cause health concerns when used for the intended application and according to the recommendations in the Material Safety Data Sheet (MSDS). MSDS’s are available upon request at 715-392- 7101 or on the AMSOIL Website. Keep Out of Reach of Children. Don’t pollute. Return used oil to collection centers.

TYPICAL PHYSICAL PROPERTIES (revised 08/07) |
AMSOIL 10W-40 100% Synthetic Motor Oil (AMO) |
Kinematic Viscosity @ 100°C, cSt (ASTM D445) |
14.4 |
Kinematic Viscosity @ 40°C, cSt (ASTM D445) |
84.5 |
Viscosity Index (ASTM D2270) |
178 |
Cold Crank Simulator Apparent Viscosity @ -25°C, cP (ASTM D5293) |
5429 (-25) |
Pour Point °C (°F) (ASTM D92) |
-43 (-45) |
Flash Point °C (°F) (ASTM D92) |
230 (446) |
Fire Point °C (°F) (ASTM D92) |
250 (482) |
Four-Ball Wear Test (ASTM D4172: 40kgf, 150°C, 1800 rpm, 1 hr) Scar diameter, mm |
0.406 |
Noack Volatility (ASTM D5800) 250°C for 1 hour, % weight loss |
6.7 |
High Temperature/High Shear Viscosity cP, X°C, X s-1 (ASTM D4683) |
4.3 |
Total Base Number |
>12.1 |

Technical Service Bulletin
Date: 8/3/2007
Subject: Flat Tappet and Camshaft Lobe Lubrication
Technical Service Bulletin
Product Description: AMSOIL Synthetic Motor Oils
OBJECTIVE:
Provide facts outlining lubrication requirements of flat tap-pet and camshaft style engines and the effect of motor oil additives containing higher levels of zinc/phosphorus.
ISSUES:
Engine oils contain anti-wear additives and the most com-mon anti-wear chemistry is zinc dialkyldithiophosphate (ZnDDP), which contains a combination of zinc and phosphorus. In 2005, in an effort to guarantee catalytic converter performance in new vehicles, the American Petroleum Institute (API) and International Lubricants Standards Approval Committee (ILSAC) instituted API SM and IL-SAC GF-4 quality standards which reduced the maximum limit for phosphorus to 0.085% and 0.080% respectively. Both API SM and ILSAC GF-4 specifications also contain a minimum phosphorus content of .065% and .060%.
Previously, API SL/ILSAC GF-3 oils were restricted to 0.10% phosphorus level, so a concern arose that oils containing lower levels of zinc/phosphorus could provide insufficient protection in high pressure areas of flat tappets and camshaft lobes found in many older cars and high-performance engines.
TECHNICAL DISCUSSION:
Proper assembly lubes and oil additives should be used during the break-in phase for all new or rebuilt engines with flat tappets. These additives provide the extra protection required at the point of contact during break-in to help the flat tappet face to properly mate with the cam lobe. Once the break-in phase is completed, these additives should not be used because of other engine life issues created by long term use of these materials. AMSOIL does not provide break-in assembly lubricants, but one of the common products is GM E.O.S., which is an assembly lubricant and is not, as stated by GM, an engine oil additive. AMSOIL does not recommend using any engine oil additives with AM-SOIL engine lubricants.
High-performance modified engines benefit from oils with superior film strength and anti-wear properties. The flat tappet/camshaft lobe interface is the one area in an engine that has extreme contact load. This load increases significantly where non-stock, high-pressure valve springs are employed so the use of properly formulated engine lubricants is extremely important to reduce wear and extend flat tap-pet/camshaft life. In these applications, AMSOIL recommends motor oils containing high levels of zinc/phosphorus for superior protection.
RECOMMENDATION
| AMSOIL Product Name |
Phosphorus Level
(ppm) |
Zinc Level
(ppm) |
| AMO 10W-40 Synthetic Premium Protection |
1265 |
1378 |
| ARO 20W-50 Synthetic Premium Protection |
1266 |
1379 |
| HDD Series 3000 Synthetic 5W-30 Diesel Oil |
1266 |
1379 |
| TRO 20W-50 Synthetic Racing Oil |
1235 |
1370 |
| AHR SAE 60 Synthetic Racing Oil |
1265 |
1375 |
AMSOIL AMO, ARO, HDD, TRO, and AHR all contain high levels of zinc/phosphorus maximizing flat tappet/camshaft life in stock and modified applications.
AMSOIL 10W-40 (AMO) and 20W-50 (ARO) are premium synthetic formulations which are recommended for API SL (gasoline)/CI-4 Plus (heavy-duty, on-road diesel) specified applications. They are an outstanding choice where high zinc containing protection is required in late model hot rods requiring extra camshaft protection.
AMSOIL (HDD) is a 5W-30 weight combination diesel/gasoline oil with a higher starting TBN to handle the significant stresses from high soot loading and acid generation in modern diesel engines. HDD contains the high phosphorus and zinc required for long life.
AMSOIL 20W-50 (TRO) is a premium synthetic racing oil with superior film strength and anti-wear protection for gasoline engines. It is an excellent choice for street or race cars, hot rods, trucks or boats. TRO is the preferred choice for highly modified, high horsepower engines requiring the extra protection required by flat tappet camshaft engines.
AMSOIL (AHR) is a super heavy weight racing oil de-signed for alcohol and nitro burning race engines where viscosity loss associated with fuel dilution is a concern. AHR includes a high dose of zinc containing anti-wear chemistry that race engines require.

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