I pretty much only run the hitec 985MG. Fast, strong and water resistant. Great servo for $70.
When new, I still pull them apart and put a light coat of RTV on all the o-ring seals so I know they are well seated and sealed. I also put a bit around the input wire boot.
Run in snow, water, mud and no issues. I run them as my t/b servos on my savage and aftershock. May be running two in a slayer I have coming in the mail. One for steering, the other for t/b.