New guy to the site. Love it..Anyhow here is my question ( and not wanting start a big fight) I have read all the post about oil, and alot of the members are using the Rotella oil, I went to the local Wal-mart they had the 15-40 Rotella, not syn. and that was all. It looks like it is used for Diesel engines, Not being a gear head,(lucky to change my own oil) will this work in a 2007 GL1800. Most of the post talk about the syn., they had the Mobil 1 syn. I work for a John Deere dealership, and they have John Deere 15-40 +50 that they used for all the John Deere equipment. So there is my question: will oil made for Diesel motors work in a GL1800? Like someone said when you buy a $20000.00 Goldwing what's another $20.00 for good oil. Thanks in advance..