To provide a fuel oil additive which can give in a small amount a fuel oil maintaining an excellent lubrication performance and not causing a trouble in the fuel jet pump of a Diesel engine, such as rust development, even when the fuel oil is especially a gas oil having a reduced sulfur content.
This additive for an ultra low sulfur content fuel oil having a sulfur content of ≤0.005 wt.%, containing as essential components (A) a lubricity-improving agent having a solubility parameter(SP) of 9.0 to 9.3, a HLB value of 0.5 to 1.7, an average mol.wt. of 250 to 300, an acid value(AV) of 180 to 210, and an iodine value of 60 to 188, (B) an antioxidant having a chain transfer constant of 0. 001 to 100 and an SP value of 8.0 to 12.0, (C) a flowability-improving agent, and (D) an aromatic compound having an SP value of 8.9 to 9.4.
OTA YOSHIHISA
