I bought my bike (1995 model) a couple of weeks ago and I am ready to change the oil. Here’s my question. The previously owner always used “motorcycle oil” and said that I should continue with the same oil. But after reading the Vulcan Verses it seems like an oil such as Shell 15W-40 "Rotella T" works fine with the VN750. I’d rather use the Shell 15W-40 "Rotella T" because it is easily bought at the local Walmart. Who is right?