AMSOIL DOMINATOR® 5W-20 100% Synthetic Racing Oil

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AMSOIL DOMINATOR 5W-20 100% Synthetic Racing Oil

AMSOIL DOMINATOR 5W-20 Synthetic Racing Oil is the lightest grade in the DOMINATOR race-oil family, built for high-performance gasoline race engines that call for an SAE 20 viscosity and want a thinner film at high rpm. Track tuners running modified small-block, bracket, asphalt late model and midget programs use the 5W-20 grade to chase ring-seal recovery and bearing speed without giving up the high-zinc, high-phosphorus chemistry that race-only formulations carry. This is a race-only oil and is not intended for long-term use in passenger cars and light trucks.

High-zinc anti-wear chemistry for race-only valvetrains

DOMINATOR 5W-20 is heavily fortified with zinc and phosphorus anti-wear additives that load the cam lobes, lifter faces, rocker tips, wrist pins and ring pack with a sacrificial film before metal-on-metal contact can occur. Independent four-ball wear testing per ASTM D4172 (40 kg load, 150 C, 1,800 rpm, one hour) measures a 0.40 mm wear scar on the 5W-20 grade, supporting aggressive flat-tappet camshafts, high-spring-pressure roller cams and shock-loaded valvetrains common in oval-track and bracket programs. Because DOMINATOR runs above the API ZDDP cap, no aftermarket ZDDP, moly or generic race-oil additive is needed, or recommended, on top of the formulation.

Thin film, real SAE 20 protection at temperature

A high-revving race engine wants the lightest film it can run without losing bearing protection. DOMINATOR 5W-20 is engineered to hold an in-grade kinematic viscosity of 9.1 cSt at 100 C per ASTM D445 and a high-temperature, high-shear viscosity of 3.1 cP at 150 C per ASTM D5481. Shear-stable synthetic chemistry resists viscosity loss from valvetrain and bearing shear, so the operating film stays inside the SAE 20 window from green flag to checkers rather than thinning out into a 10- or 15-weight film by the end of a long feature.

Proprietary friction modifier for measurable horsepower

Lower internal friction frees up crankshaft horsepower and pulls heat out of the bearings, valvetrain, and timing drive. DOMINATOR 5W-20 uses a proprietary friction modifier to reduce parasitic drag inside the engine, helping the formula deliver maximum horsepower at cooler oil temperatures. The same DOMINATOR Synthetic Racing Oil that goes into the engines of AMSOIL corporately sponsored racers, including Bryce Menzies and Brad Lovell, is the same oil shipped in retail quarts on this page.

Cold flow and thermal headroom

A pour point of -48 C (-54 F) per ASTM D97 and a cold-crank simulator viscosity of 5,347 cP at -30 C per ASTM D5293 mean DOMINATOR 5W-20 lays down a protective film fast on a cold fire-up, so oil pressure peaks before the cam and bearings see load. At the other end, a flash point of 230 C (446 F) and a fire point of 254 C (489 F) per ASTM D92 give thermal headroom for sustained high-rpm running on hot summer features. Viscosity index of 159 per ASTM D2270 keeps the operating film flat across a wide oil-temperature swing across qualifying, heat, and feature laps.

Fuel and chemistry compatibility

DOMINATOR 5W-20 is compatible with leaded and unleaded gasoline, diesel, alcohol, nitromethane, and nitrous oxide. The synthetic base resists fuel dilution, varnish, and ring-zone deposits that build quickly when running rich, on lead, or under heavy nitrous load. Total base number of 8.0 supports the acid-neutralization workload from combustion blow-by during long bracket runs and endurance events.

Recommended applications and service intervals

DOMINATOR 5W-20 is built for domestic and import high-performance racing engines that call for an SAE 20 viscosity. Typical builds and series include:

• Modified small-block
• Bracket
• Asphalt late model
• Midget

Race-engine oil service life is event- and chemistry-driven. When competing, the engine builder or vehicle owner is responsible for setting an appropriate oil change interval based on event length, fuel, rpm range, blow-by, and oil analysis. DOMINATOR is not intended for long-term use in passenger cars and light trucks; engines that see daily-driver duty should run an API-licensed AMSOIL Signature Series, XL, or OE motor oil instead. Oil analysis through Oil Analyzers Inc. (715-395-0222), a division of AMSOIL, supports interval and engine-health decisions between rebuilds. Pair DOMINATOR 5W-20 with an AMSOIL race-rated oil filter and a clean break-in protocol; aftermarket ZDDP, moly or generic "race additive" packages should not be mixed in.

Typical technical properties

Order AMSOIL DOMINATOR 5W-20 Synthetic Racing Oil

DOMINATOR 5W-20 Synthetic Racing Oil ships in quarts (product code RD20QT-EA) and cases of 12 quarts (RD20QT-CA), backed by the AMSOIL Limited Warranty for defects in materials and workmanship. For street-vehicle application match beyond a race engine, use the AMSOIL vehicle lookup guide to confirm the right viscosity, and the AMSOIL car oil guide to compare Signature Series, XL and OE motor oils for daily-driven cars and trucks. Order AMSOIL DOMINATOR 5W-20 100% Synthetic Racing Oil.

Frequently asked questions