You can run an API-SA-rated oil you found in your great-grandfather's garage in your VW if you like. API and ACEA have updated to LSPI-tested oils for a reason. ACEA A7/B7 and C6 are replacing ACEA A5/B5 and ACEA C5, respectively, and it looks like VW 508.00 has been updated to modern mixed calcium–magnesium detergents as well. There is no reason to run an outdated oil, which may not protect a TDGI engine from possible LSPI events. Moreover, in addition to providing LSPI protection, mixed calcium–magnesium detergents protect against acid build-up better than calcium-only detergents, extending the OCI and increasing engine life. That's because calcium and magnesium neutralize different kinds of acids and work well in synergy.