Synthetic ATF has a couple benefits, including more resistance to overheating... I guess if I was going to leave it in for 30K I would go to a Synthetic ATF: Redline, M1 or Amsoil.
NOTHING in a can or bottle will fully repair a mechanical defect.
I'm in the middle of an Auto-Rx transmission application on my SVX: I 1st changed out the ATF fluid (with Castrol), back-flushed the cooler, then changed the filter and hoses. I plan to run it 1,000 to 1,200 miles as per their instructions, replace basically all the fluid by dropping the pan, replacing the internal tranny screen/filter, refill & run a dozen quarts through using the return hose from the cooler when I change the ATF filter, again...
Using Chevron Dextron III as it was 79 cents per quart. I don't find the fluid replacement any more complicated than an oil change. I mean DUH! there is a drain plug and a hose from the cooler with a hose clamp to unhook: not exactly brain surgery...
I kept the ATF filter from the initial change and will be cutting them both open to compare. My transmission (a factory rebuilt replaced under warranty in 1998 @ 57,xxx miles) has never given me a problem (I'm sure it had all the relevant upgrades) and the fluid (which I normally changed every 15-20K) has always been clean, pink and unburnt. Routine maintenance is certainly the key to reliability & good performance, IMHO.
I'll probably put my new radiator in at 120K when I replace (or HAVE replaced) the timing belt, water pump, maybe the cam & crank seals... My last repair on the crack at the radiator valley seems to have finally been 100% successful. I got a deal on the new factory radiator and since I plan on driving & enjoying the SVX for the forseeable future it seemed a reasonable investment.
Admittedly I don't feel we are very "hard" on our SVX, which we purchased new 116K ago. I go much faster on my ZX-11...
Last year's 6K+ cross-country trip was a PURE DELIGHT. I was never more impressed with the SVX than when I drove non-stop (except for gas in, gas out) from Denver to PDX in 22 hours. That was including (rear) wheel bearing getting noisey in Wyoming @ 85 mph in a downpour ( about 8 inches of water on the highway! WHEEEEE!!!!!!!!!)! Rum-rum-rum-rum-rum... RUM-RUM-RUM!
I've used Auto-Rx previously in the oil in the SVX, my Ford F250 (both the 460-carb & in the C6 as we speak), the '73 450SE(oil & tranny), the oil in the 420SEL (had just had a MB transmision service when I found out about Auto-Rx) and it is in the wet-clutch ZX-11now, too.
In my opinion & in my experience it works as advertized and I don't hesitate to recommend it to anyone. IT WILL NOT FIX A MECHANICAL DEFECT OR PROBLEM. It WILL gently clean your engine or transmission. Seems to work on leaks from rotating seals (like cam seals), too... It did for me.
Cheers!