BannedCR500Riders.com

My 87 CR500 is all stock, all original. The fork seals are starting to seep and it rides a bit low in the stroke (probably due to low oil volume). The forks are super soft, maybe a bit too soft. I'm getting within 4 inches of bottoming out just from hauling ass on smooth dirt hills... The rear seems fine, but is a little bit rough over choppy high speed bumps. It is definately out of balance, the front just seems too soft and the rear end it a bit too stiff. I'm 6'1" about 185 with riding gear on. I think I'm about on the border of needing heavier fork springs.

Has anyone on here tried the speed sensitive oil from http://www.smartperformanceinc.com/ ?

My friend with a YZ250 loves this oil and swears by it, but I'd like the opinion of more "normal" riders, because my friend is a much faster rider than myself. I prefer just trail riding and hillclimbs, I'm almost never on a motocross track.

I can get the forks and shock revalved for my weight and riding style and rebuilt for ~$500 from smart performance, or I could just rebuild them myself and install the speed sensitive oil. Which would you guys go with?

Your springs are probably sacked.
Face it, they're old.
If you're not on a track you probably want a soft ride but not sacked.
Have you tried just adding a little air?
You can put a couple of pounds in and it makes a big difference.
I can't find a free length measurement in the manual for the fork springs.
The oil will affect the speed of action for the most part.
If it were me, I would experiment with a little heavier oil and air pressure.
If I were racing it, yeah I'd send it out and spend the money.

The forks are easy to rebuild. I'd order the springs (for your weight), bushings and seals since they're all probably worn out. Those forks deliver a pretty sweet ride when setup correctly.