Outlet guide vane for aircraft turbomachine, with improved lubricant cooling function

A guide vane (24, fig 2) suitable to be positioned in a twin-spool aircraft turbomachine fan, comprising an aerodynamic flow straightening part (32) located between the root (34) and the tip (36). The aerodynamic part comprises a lubricant cooling passage (50a) which extends in a first lubricant flow direction 52a from the root to the tip of the blade and is limited by intrados 70 and extrados 72 blade walls. The aerodynamic part is made in a single piece. It comprises heat transfer fins 80a, 80b, which connect said walls and extend parallel to the first direction. The fins are distributed in successive rows in the first direction. For a first row R1 and a second row R2 of staggered directly consecutive fins, the first row comprises several fins 80a which form a positive acute angle A1 with a plane and the second row comprises several fins forming a negative acute angle A2 with the same plane, where said plane is a dummy reference plane Pf of the vane which is parallel to the first direction.