The issue with 7-series (and 5 series with 4.4L engines) was with gasoline engines. BMW has not had a single failure with Nikasil blocks in Europe and massive rate of failure in the US. This resulted in them switching to Alusil and offering to replace the blocks with a new one upon leakdown test failure.Sulphur? I thought that was only an issue with US Diesel fuel. Never heard of Sulphur levels being an issue in US gasoline.
The E38 isn't a Diesel is it? I don't recall ever seeing a 7-series BMW Diesel in the US, so prolly not.