I ride my 81 xs650 year-round in kansas. I have run 20-50 cycle oil exclusively for the last.five years. No major complaints but wondering if there might be something better for hot weather.
First of all, I just noticed that this is your first post. Welcome to the site. I've owned my 650 for many years and thought I knew everything I needed to know about it. Boy was I wrong. The level of expertise here is amazing.
It's funny your first post is about oil. There are several long threads on oil selection. The only thing you could ask about that could cause more discomfort is the buckhorn vs low handlebars. Two camps here. The buckhorn gang is very active.
Heres what I know. Take it with a grain of salt. Back in the 70's I used GTX in all my bikes. I grew up in Houston and I don't think it could get any more stressful on the oil than 70's boomtown traffic when it was 95 or better. Never had any trouble.
Thing is something changed when automobiles started using catalytic converters. The zinc in the oil that helped prevent wear in the transmission was poisoning the cats and most of the zinc was removed from most oils. In addition friction reducing additives were introduced to improve fuel economy that wet clutches did not get along with. So everything I knew about oil went out the window.
Castrol no longer recommends GTX for bikes . They have several bike specific oils that have higher zinc levels.
I figure that Castrol finds out more about oil in a day then I will in my lifetime so who am I to argue.
The bike oil is more expensive but 2.5 quarts price difference isn't going to break me.
If you want to know more do a search for oil and prepare for a evening sorting through it.
Cheers
Jack