What oil viscosities are recommended for Ford gasoline engines by temperature?

The gasoline engine chart lists SAE 30, 20W-20, 20W-40, 20W-50, 10W-30, 10W-40, 10W, 5W-30, and 5W-20, each matched to the temperature range you expect before the next oil change (from about −20°F/−30°C up to 100°F/30°C).

What oil grades does the chart show for diesel engines?

The diesel engine chart shows SAE 30 for warmer temperatures and SAE 10W-30 for colder temperatures, across a range of roughly −20°F to 100°F (−30°C to 40°C).

What API service classification of oil should be used?

The document states that only oils designated for Service SG heavy duty detergent use should be used in the truck.

Can non-detergent or straight mineral oils be used?

No. The caution box states that non-detergent motor oils or straight mineral oils should not be used in your Ford gasoline engine.

What does the 'W' in 10W-40 mean and how does multigrade oil behave?

The W stands for winter. A 10W-40 oil acts like a 10 weight oil when the engine is cold, allowing easier cranking and quicker lubrication, and like a 40 weight oil at operating temperature, providing heavier lubrication with less foaming.

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Ford Truck Engine Oil Viscosity Chart - SAE Grades for Gas & Diesel (Fig. 90)

Service manual page on engine oil viscosities with SAE viscosity-grade temperature chart Fig. 90

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Scanned service manual page covering engine oil viscosities, with an SAE viscosity-grade versus temperature chart and prose on multigrade oils.

AI caption July 2017 · Photo 185 of 205

This scanned repair-manual page (labeled Fig. 90, "Engine oil viscosities") presents two temperature-based SAE viscosity grade charts for Ford trucks — one for diesel engines and one for gasoline engines. The diesel chart recommends SAE 30 for warmer temperatures and SAE 10W-30 for colder ranges, keyed to ambient temperature scales in both °F (−20 to 100) and °C (−30 to 40). The gasoline chart lists SAE 30, 20W-20, 20W-40, 20W-50, 10W-30, 10W-40, 10W, 5W-30, and 5W-20 grades matched to the temperature range expected before the next oil change. The accompanying text explains how multigrade oils work — behaving like a light (e.g., 10 weight) oil when cold for easier starting and quicker lubrication, then like a heavier (e.g., 40 weight) oil at operating temperature. It also explains API service designations, stating that only Service SG heavy-duty detergent oils should be used, describing how SG oils use metallic detergents and polymeric dispersants to prevent deposits, suspend sludge and dirt, and neutralize combustion acids such as sulfuric acid. A caution box warns that non-detergent motor oils or straight mineral oils must not be used in Ford gasoline engines. A reference number, 85761079, appears beneath the charts.

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Frequently asked questions

What oil viscosities are recommended for Ford gasoline engines by temperature?: The gasoline engine chart lists SAE 30, 20W-20, 20W-40, 20W-50, 10W-30, 10W-40, 10W, 5W-30, and 5W-20, each matched to the temperature range you expect before the next oil change (from about −20°F/−30°C up to 100°F/30°C).
What oil grades does the chart show for diesel engines?: The diesel engine chart shows SAE 30 for warmer temperatures and SAE 10W-30 for colder temperatures, across a range of roughly −20°F to 100°F (−30°C to 40°C).
What API service classification of oil should be used?: The document states that only oils designated for Service SG heavy duty detergent use should be used in the truck.
Can non-detergent or straight mineral oils be used?: No. The caution box states that non-detergent motor oils or straight mineral oils should not be used in your Ford gasoline engine.
What does the 'W' in 10W-40 mean and how does multigrade oil behave?: The W stands for winter. A 10W-40 oil acts like a 10 weight oil when the engine is cold, allowing easier cranking and quicker lubrication, and like a 40 weight oil at operating temperature, providing heavier lubrication with less foaming.