Originally Posted By: barryh
I know oils are self certified to the ACEA specs but where for example they are incorporated into an OEM spec for example MB saying that a 229.3 or 229.5 oil must meet ACEA A3/B4, surely we can safely assume that they really have tested that the oil meets A3/B4.
Only if the OEM lists the oils as approved, or in the case of VW, a VW list includes the oil in terms of which of their specs it is supposed to comply with.
The major brand oil companies like Mobil, Castrol, Shell (Inc Penn and other Sopus group companies) and Liqui Moly seem to be reliable in terms of "Recommended For" lists and have tested the oils correctly several times to rule out batch variability. Also they do repeat the tests if they change the base stock mix.