Treat your diesel right with Freedom Series 100% Synthetic Diesel Oil. Freedom Series emerged when AMSOIL and Fleece Performance Engineering partnered to develop an advanced formulation for diesel pickup trucks equipped with Fleece Performance products. Freedom Series Synthetic Diesel Oil provides excellent turbo cleanliness, superior soot control, and outstanding wear protection. The result: protection engineered to perform.
Add an AMSOIL Preferred Customer membership to the same cart to unlock up to 25% off qualifying products. Existing members can sign in, and qualifying orders currently over $100 can ship free.
Product data sheets
View, download, or save a copy of the Product Data Sheet or Safety Data Sheet for Freedom Series 5W-40 100% Synthetic Diesel Oil.
Freedom Series 5W-40 100% Synthetic Diesel Oil (FD540) is an advanced full-synthetic diesel formulation co-developed by AMSOIL and Fleece Performance Engineering for turbodiesel pickups specifying API CK-4 (and prior). The 5W-40 grade is the broad-temperature pickup-diesel viscosity, well suited to towing, hauling, and tuned trucks running Fleece Performance components, with strong cold-start flow and stable high-temperature protection. Freedom Series is built to deliver turbo cleanliness, soot control, and wear protection in the demanding service typical of late-model diesel pickups.
Built around the Fleece Performance partnership
Freedom Series Synthetic Diesel Oil emerged from a development partnership between AMSOIL and Fleece Performance Engineering. The formulation is targeted at diesel pickup trucks equipped with Fleece Performance products, where the oil sees added thermal load, longer turbo spool times, and elevated soot generation from aggressive duty cycles. The product applications statement covers turbodiesel engines specifying API CK-4 and prior categories, equipped with Fleece Performance Engineering products.
Wear protection in demanding diesel service
Wear on rings and cylinder liners drives oil consumption up and pulls compression, horsepower, and fuel economy down. Freedom Series is formulated to deliver outstanding wear protection in demanding operating conditions, helping maximize the life of the engine and reduce maintenance cost and downtime. The 5W-40 grade carries a high-temperature/high-shear viscosity of 3.9 cP (ASTM D5481) and a kinematic viscosity at 100 C of 14.4 cSt (ASTM D445), keeping a robust hydrodynamic film between rings, liners, journal bearings, and cam lobes during heavy load and elevated oil temperatures.
Soot control and viscosity stability
Soot buildup in a diesel pickup can reduce power, increase abrasion, cause emissions-system problems, and decrease fuel economy. Freedom Series is naturally resistant to oxidation and the thickening effects of soot contamination. Boosted detergent and dispersant additives keep soot particles suspended independently, which helps prevent the formation of the larger, wear-causing agglomerates that grind on liners, lifters, and rings. Viscosity increase is minimized and soot-related wear is controlled, supported by a Total Base Number of 10.5 (ASTM D2896) for acid neutralization across the drain interval.
Turbo cleanliness for tuned and towing trucks
Turbocharged diesels punish the oil at the bearing and ring belt, especially when towing heavy loads or running aftermarket horsepower tunes. Freedom Series Synthetic Diesel Oil provides the turbo cleanliness needed to support reliability when towing, hauling, or modifying for additional horsepower. Sulfated ash content is held to 1.0 percent by weight, keeping the chemistry within the API CK-4 ash window for use with diesel particulate filters and modern aftertreatment systems.
Cold-start flow and hot-temperature stability
Freedom Series effectively resists thermal breakdown, and unlike conventional oils it contains no wax. The 5W-40 grade reaches a CCS viscosity of 6,260 cP at -30 C (ASTM D5293) and a pour point of -41 C, -42 F (ASTM D97), with a viscosity index of 150 (ASTM D2270) and a kinematic viscosity at 40 C of 88.7 cSt (ASTM D445). The synthetic base oil stays fluid in sub-zero temperatures for easier starting, improved oil flow at start-up, and reduced cold-start wear, while resisting thinning and shear loss at peak operating temperature.
Oil consumption and combustion-chamber cleanliness
Lower volatility means less of the oil evaporates off the ring belt and passes into the combustion chamber as oil vapor. Freedom Series 5W-40 records a NOACK volatility of 12.0 percent weight loss (ASTM D5800), reducing the share of light fractions that burn off and contribute to oil-derived deposits and intake-side fouling. Less evaporative oil consumption also helps the formula retain its working viscosity and additive concentration through high-temperature service.
Recommended applications and service guidance
Use the live AMSOIL product page and your owner's manual to confirm the current viscosity, API category, OEM approvals, and service guidance for your engine before ordering. AMSOIL updates approvals and recommendations as formulas and manufacturer requirements change.
For extended service, follow the current AMSOIL guidance, your equipment manual, and oil-analysis results. Extended intervals are not appropriate for every engine or operating condition, especially modified engines, unusual fuels, racing use, or equipment with special service restrictions.
Typical technical properties
Property
Value
Kinematic Viscosity at 100 C, cSt (ASTM D445)
14.4
Kinematic Viscosity at 40 C, cSt (ASTM D445)
88.7
Viscosity Index (ASTM D2270)
150
CCS Viscosity, cP at -30 C (ASTM D5293)
6,260
Pour Point, C (F) (ASTM D97)
-41 (-42)
NOACK Volatility, percent weight loss (ASTM D5800)
Order Freedom Series 5W-40 100% Synthetic Diesel Oil
Freedom Series 5W-40 100% Synthetic Diesel Oil is available in a quart bottle (FD540QT-EA) and a case of twelve quarts (FD540QT-CA). Using AMSOIL synthetic lubricants does not void a new vehicle or equipment manufacturer warranty, and all AMSOIL lubricants and filters are covered by the AMSOIL Limited Warranty. Match this grade to the engine and emissions hardware with the AMSOIL Diesel Oil Guide, match the right product in the AMSOIL Vehicle Lookup Guide, then order Freedom Series 5W-40 100% Synthetic Diesel Oil.
Frequently asked questions
Is Freedom Series 5W-40 only for Fleece Performance-equipped trucks?
The Freedom Series application statement targets turbodiesel engines specifying API CK-4 or prior categories and equipped with Fleece Performance Engineering products. The line was co-developed with Fleece Performance for that specific use case. Trucks without Fleece Performance components are better matched to a Signature Series Max-Duty or Heavy-Duty diesel grade in the OEM-specified viscosity.
Is 5W-40 a good viscosity for diesel pickups?
5W-40 is a common pickup-diesel grade for late-model trucks that need broad-temperature performance: enough cold-start flow at sub-zero ambient temperatures and a 40-grade high-temperature viscosity for towing, hauling, and tuned operation. Always match the engine manufacturer's specified viscosity before changing oil. Freedom Series 5W-40 also supports the FD1030 (10W-30) and FD1540 (15W-40) grades within the same product family for engines that call for those viscosities.
Which API specifications does Freedom Series 5W-40 meet?
Freedom Series 5W-40 is built for turbodiesel engines specifying API CK-4 and prior diesel service categories. Confirm the exact API category and any OEM specification required by the engine builder before changing oil.
How long can Freedom Series 5W-40 stay in service?
Freedom Series 5W-40 is recommended for the drain intervals stated by the vehicle manufacturer in the owner's manual. The product is not specified for extended drain intervals beyond OEM recommendations. For competition use, the vehicle owner is responsible for determining the appropriate service interval based on operating conditions and oil analysis.
Can Freedom Series be mixed with conventional or other synthetic diesel oils?
Freedom Series Synthetic Diesel Oil is compatible with other conventional and synthetic engine oils, but mixing reduces its performance benefits. Aftermarket oil additives are not recommended for use with AMSOIL synthetic diesel oils.
Will running Freedom Series void a new diesel engine warranty?
No. Using AMSOIL synthetic lubricants does not void a new vehicle or equipment manufacturer warranty, and all AMSOIL lubricants and filters are covered by the AMSOIL Limited Warranty.
How does Freedom Series 5W-40 compare to Signature Series Max-Duty?
Signature Series Max-Duty is the top-tier line for heavy-duty on-road and off-road diesel service across pickups, fleet trucks, and commercial equipment, with extended drain intervals supported in qualifying applications. Freedom Series 5W-40 is the Fleece Performance partnership formulation aimed specifically at diesel pickup trucks equipped with Fleece Performance products, run on the OEM drain interval. Use the AMSOIL Diesel Oil Guide to compare diesel oil families before ordering.
