Hydraulic Clutch Fluid

I know many of us standard tranny drivers have had slave cylinder problems.
I have researched and come to the conclusion that standard DOT3 brake fluid MAY speed up the deterioration of the slave cylinder. Many other jeepers, ,mechanics and even the auto industry has switched to DOT4 fluid for clutches now.

What's your opinion?

I am replacing my 3rd slave cylinder in 5 years and will not use DOT3 in this one.

LucasGirling DOT4 fluid was highly recommended, but it not available anywhere in my area, Castrol GTLMA isn't made anymore. The Valvoline synthetic stuff is next on my list, then I resort to the NAPA DOT4 fluid.

Discuss!

Military changed to syn fluid in the brake systems about 85 or so, I remember one weekend of driving M151's down to Bordentown NJ from our armoury, we had like 50 to do. Drive down, pull in, they would hookup a 4 wheel bleeder, suck all the fluid out, run some kind of cleaner thru and then start feeding in the synthetic red stuff. Took about 15 min per 1/4 ton. Made that trip too many times. No difference in the braking that I noticed but it made the shop mechanics happy, no more seized brakes. On a few they replaced the whole brakeline setup too. Part of the change was a pressure test for corroded lines.