I got a link to this thread from another discussion.
I found some information courtesy of Caltex
In December 2012, ACEA amended its some of its definitions such that ACEA C3 has become mutually exclusive with ACEA A3/B3 and A3/B4. The changes were made to emphasize the fact that today, the ACEA A3/B3 and A3/B4 Sequences are primarily intended for applications where lower quality, higher sulfur content fuels are in use.
Thus ACEA A3/B3 and A3/B4 claims are no longer made for Havoline Fully Synthetic C3 SAE 5W30, which is primarily an ACEA C3 oil. However, it remains suitable for use in those applications calling for ACEA A3/B3 or A3/B4 oils where it has previously been used, and where low sulfur fuels are being burned