The old Castrol Edge Extended Performance (EP) C5/MB 229.71 0W-20 SP gold bottle (?) actually also met ACEA C6 without reformulation; so, you were good from the beginning!
I put a question mark above because it is not clear in the PDSs if Castrol is actually referring to the EP gold bottle. I am guessing that this is the case because of the Euro-OEM approvals. If that's really the case, you certainly can't go wrong with the Castrol Edge EP 0W-20 SP gold bottle, as it meets the strictest 0W-20 specifications and claims a 20,000-mile OCI.
In addition to providing LSPI and timing-chain protection, ACEA C6 reduces the valvetrain wear by 18% with respect to C5, improves the fuel economy, and reduces the engine and turbocharger deposits.
The new ACEA A7/B7 and ACEA C6 categories are the most advanced ACEA categories and provide the least wear and cleanest engines—more so than any other ACEA category.
Oronite OLOA 54720 additive package meets BMW LL17FE+, MB229.71, Volvo RBS0-2AE 0W-20, WSS-M2C947-B1, WSS-M2C962-A1, ACEA C6, and API SP/RC (ILSAC GF-6).
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The HTFS/VII table lists all the Castrol 0W-20 flavors. The flavors to avoid are Castrol Edge High-Mileage 0W-20 SP and Castrol GTX Full Synthetic 0W-20 SP.
It is theorized that the wear for the following engine components depends on these variables among other things: Bearings: high-temperature, high-shear (HTHS) viscosity, TBN/TAN/base-oil oxidation performance (lead and copper corrosion) Piston rings: base-oil viscosity, TBN/TAN/base-oil...
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