Actually, oils high in ester (POE) content tend to increase engine wear because when the ester clings onto the engine parts, it prevents the AW/EP/FM additives from clinging onto them. However, small amounts of POE is OK. For example, Mobil 1 FS and ESP oils have a small amount of POE in them. It helps increase the thermal stability of the oil, but primarily, it increases the engine cleaning through higher solvency of POE. That said, you don't need to have POE in your oil. Motul 8100 X-clean+ 5W-30 is an excellence choice. In
@Trav's case, cleaning power of the POE helped with his varnish and oil consumption issues by removing the deposit build-up. M1 ESP and FS oils, as well as the Motul Ester Core oils, have about 5–7% POE. Motul 8100 X-clean+ 5W-30 does not have POE.