Lubricity indices, wear rate, resistance to oxidation (95degreesC, 3 L O-2/h; in a toothed gear 1450 rpm, 155degreesC, 1 L air/h, 50 h), and to catalyzed oxidation (Al, Mg, Cd, Fe, and Cu as metal catalysts, 135degreesC, 5 L air/h, 168 h), and resistance to corrosion (100degreesC, 5 L air/h, 40 h) were examined in olelic acid dimer (I), its Me ester (II) and estolide (III) and estolide Me ester (M, low-erucic acid rapeseed-oil fatty acid dimers, their Me and i-Bu esters, and hydroxy and hydroxy-methoxy derivatives. Flow temperatures were lowest and viscosities were highest in III and IV (Fig. 1, Table 1), steel-ball wear rates were lowest in I and III as medium (Table 2). As lubricant, I was best. Most resistant to corrosion were I, III and IV (Tables 4, 5), but I and III were not resistant to oxidation. I and III seem best as potential basis oils or potential components of proecological working fluids and lubricants.