Size selectivity of Candida antarctica lipase B (CAL-B) was examined in the acylation of pentaerythritol with oleic acid. Biolubricant mixtures consisting of mono-, di-, tri-, and tetraoleates were expected in variable excess. Enzymatic tetraoleate formation was suppressed under solvent conditions; however, this size selectivity was lost without solvent and tetra-acylated pentaerythritol accumulated in up to 93%. The lipase caused size selectivity persisted over a broad temperature range from 35 to 95 °C. A Fischer–Speier esterification showed that substrate bulkiness was only a minor contributor to observed size selectivity. All in all, switch on/off size selectivity using CAL-B allowed to vary pentaerythritol biolubricant compositions in an unprecedented manner.