When I lived in had a Toyota 4Runner in the 1990's I had to once a year take some SS steel wool and run it over my whip. When I would be washing Ga. red clay or Michigan Road Salt off I would hit with some NuFinnish poly/wax. I never saw rust on it just the normal whiteish film all stainless steel forms to protect itself. It is 3:50am and I have been drinking beer I can not think of the name of the sacrificial coating SS forms. LOL I have a really nice white K40 base loaded antenna but my radio has an MRF455 as it's final and I just do not trust the capacitor inside the base. If I decide to run power than I trust it even less since my 1 pill cranks out about 220 watts rms. Transistors are just too darn expensive. I remember when a Toshiba 2SC2879 was $12 now they are $64. On top of that if I decide to break the law and wonder off 11m the K40 has terrible swr off freq.!
I'm not going to touch the 1 pill 220 watts rms comment but I will say that I've had a 102" whip on my little 94 civic for over 2 years and have not noticed any corrosion or film on it. The regular steel spring was rusting and left a rust mark on the trunk that wouldn't wash away but nothing from the stainless steel mount or the whip. This includes 2 winters with Illinois salt and plenty of rain. Mine was a radio shack 102" on a 6" spring I bought for cheap from years back when sparky's was still a reputable (and open) shop. I know there are more than one formula of stainless steel which makes me wonder if perhaps we had different stainless whips. I just received my 108" whip from mfj tonight and I can say that it is in fact close to 108" so they DO make 108" whips. I stood it against my 102 with the old 6" spring and it was actually slightly longer. I'm not sure if I am a fan of the set screws in the base to hold the whip as I read a solid antenna in the description. It's not big deal as I can take it to a nearby shop to have them tig it solid. Just adding my 2 cents.
73s from 309 in the land of Lincoln.