Originally Posted by NoTempoLimitN54
Greetings from a former Miami-dweller who can now afford a recent model BMW (I had to move out of Miami to make that happen).
LONG story on this one. A full explanation will be too lengthy. Search for threads on this. But in brief: As a result of a lawsuit (Castrol vs. Mobil)/trade dispute/arbitration, etc., type III motor oils that meet certain performance requirements can be labeled as "synthetic", except in Germany. Type III are very highly refined natural (dino) base stocks. Type IV are the true synthetics because the molecules are synthesized.
I think when these motor oils are labeled "full synthetic" it really means "type III base stocks or better".
The OEM BMW 5W-30 and all the Castrol Edge SPT are type III except for the "European Formula" 0W-30 "German Castrol".
I've been doing a lot of research on this lately. It seems that high quality type III motor oils are OK and it's more important to look at the performance stats for the oil (viscosity, flashpoint, HTHS, etc.)
Does anyone know and specific advantages of type IV base stocks over type III?
Gr3+ has better solubility(sp) with regards to additives and is on par with PAO in many performance specs. Most euros are a blend of gr3/4/5.