Phillips 66® Guardol Eco Diesel Engine Oil, formerly known as Firebird Heavy Duty EC, is an environmentally responsible API CK-4 engine oil developed for use in four-stroke cycle diesel engines designed to meet 2007 and later EPA on-highway exhaust emissions standards. It is specially formulated for compatibility with exhaust aftertreatment systems using diesel particulate filters (DPFs), diesel oxidation catalysts (DOCs) and/or selective catalytic reduction (SCR). It is backward serviceable for use in pre-2007 diesel engines.

You are currently viewing GUARDOL ECO® DIESEL ENGINE OIL

Features & Benefits

  • Excellent protection for newer low-emission diesel engines and older diesel engines
  • Specially formulated to protect exhaust aftertreatment systems
  • Protects against particulate filter plugging
  • Excellent soot control for protection against abrasive wear and soot-induced oil thickening
  • Excellent resistance to viscosity and thermal breakdown at high temperatures
  • Protects against sludge and varnish formation
  • Protects against rust, bearing corrosion and wear
  • Good resistance to foaming and aeration
  • Lessens the environmental impact of used oil disposal


  • On-highway diesel trucks equipped with EGR and exhaust aftertreatment systems to meet 2007/2010 emissions standards
  • Older diesel equipment with conventional, non-EGR engines or ACERT engines
  • Off-highway construction, earth moving and mining equipment

Technical Details

  • 15W-40
  • Licenses & Approvals

    Guardol Eco is licensed or OEM-certified for: #API Service CK-4, CJ-4, CI-4 PLUS, SN #Cummins CES 20086 #Detroit Diesel DFS 93K222 #Ford WSS-M2C171-F1

    Guardol Eco meets or exceeds the requirements of: #Caterpillar ECF-3, ECF-2, ECF-1-a #Mack EOS 4.5 #Mercedes-Benz Sheet 228.31 #Volvo VDS-4.5 #Diesel engines manufactured by OEMs not listed above, where the OEM specifies API CK-4 engine oil

    Additional Details

    SAE Grade 15W-40
    Specific Gravity @ 60°F 0.8774
    Density, lbs/gal @ 60°F 7.31
    Color, ASTM D1500 L 4.0
    Flash Point (COC), °C (°F) 235 (455)
    Pour Point, °C (°F) -31 (-24)
    Viscosity, Kinematic
    cSt @ 40°C 111
    cSt @ 100°C 15
    Viscosity Index 139
    Cold Cranking Viscosity, cP @ -20°C 5400
    High-Temp/High-Shear Viscosity, cP @ 150°C 4.2
    Sulfated Ash, ASTM D874, wt % 0.99
    Total Base Number (TBN), ASTM D2896 9.7
    Zinc, wt % 0.125
    Re-refined Content, Finished Oil, vol % 100
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