I have a question. Why do you think you need to change your oil every 3K?
At the risk of getting flamed consider the fact that changing oil every 3K is exactly double the frequency that is recommended by the manufacturer.
BMW uses and recommends regular dino oil. Synthetic oil users usually do so because it lasts even longer, thus justifying the extra cost.
From my rudimentary understanding all synthetic motor oil starts with a large helping of organic base stock which is a natural resource pumped from below or dug up and extracted from tar sands. The rest is chemical compounds and additives. Synthetic oils are not environmentally friendly as some folks might believe.
MJM - BeeCeeBeemers Motorcycle Club Vancouver B.C.
'81 R80G/S, '82 R100RS, '00 R1100RT