It dpnt matter, you can mix em, its just a name on the part. I run Castroil GTX 10w-30, 4 qts, and 1 qt Lucas Oil, I think its a
5w-20 or a 5w-30 weight oil. I dont run synthetic for a couple reasons, I heard its not good running synthetics in Hondas, and second, I am too poor to be changing that out after every other race. I would run Oreilly brand if I knew it wouldnt hurt the motor, haha...