What oil to put in front forks

When I bought my 77 KZ1000, one of the first things that I did was change the fork oil. I used ATF because it was cheap and I'd read it worked fine for forks. It's been a few years now and I'm going to change it again. I've searched the forums and the internet to see if fork oil would work better than the ATF. Even though my bike is a 77, the forks are from an 80 LTD.

If I switch to fork oil, what weight should I use? I weigh 175 pounds. I'm looking for a comfortable ride.

15W fork oil is what mine uses.

bountyhunter wrote: 15W fork oil is what mine uses.

+1
I've been using 15w BelRay fork oil in mine forever (I change it about every 2 years or so). It worked great 30 years ago when I weighed 170 lbs and it works great now that I weigh 200. Also, no problems riding with wife as passenger. Ed