Ford F-750 Owner's Manual page 177

Maintenance and Specifications
Diesel engines require specially formulated oil to resist contamination.
Proper quality oils also provide maximum efficiency of the crankcase
ventilation system which reduces air pollution.
For normal or severe service, use Motorcraft oil or an equivalent oil
conforming to Ford Specification WSS-M2C171–D or API Service
categories CI-4 PLUS, CI-4/SL or DHD-1. If CI-4 PLUS oil is not available,
CH-4 is acceptable.
Diesel engine oils with improved fuel economy properties (energy
conserving) are currently available. If you use an energy conserving oil,
be sure it meets Ford specification WSS-M2C171–D or API service
category designation CI-4/SL and is of the proper viscosity grade for the
temperature range in which you expect to operate your vehicle. Some
energy conserving oils do not meet the requirements necessary for your
diesel engine.
* Heavy duty trailer towing with ambient temperatures above 50°F
(10°C) requires 15W-40 engine oil.
Using the chart, determine which SAE viscosity grade best suits the
temperature range in which you expect to operate your vehicle. The use
of the correct oil viscosity grade for diesel engines is important for
satisfactory engine operation.
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2007 F-650/750 (f67)
Supplement (supplement)
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