I have a 2001 Indian Spirit. I want to change the transmission oil and the owner manual says to use Indian 80w-90 transmission oil. My service manual says 80-90 gear oil. Does anyone have an opinion on a good brand of oil to use? I also want to change the primary chain and wet clutch oil and the manual says use Indian primary oil. Again can anyone recommend the proper oil for this year bike? Thanks for any recommendations.