Agree....my dad taught me this 40 years ago on the family Dodge...just lightly smear it all over exposed areas of terminals, and your worries are gone.  Clean everything up first, bright shiny terminals and connectors, of course; scrape with knife blade or those twisty wire-brush things on inside of connector and outside of battery posts.  Make a good connection FIRST, and then PROTECT it with grease on the exterior.
Any kind of grease....just a light coating will do.  Idea is to keep corrosion away...so Vaseline, general purpose grease, whatever...on the exterior of the connection.

In general, I think starter motor batteries are good for about 8 years...not sure about deep cycle batteries.  But if no good at connections, then no good no matter how new the battery is.
Skip the silicone sealer approach.

Rich
San Diego

      From: Alistair Bell <albell@SHAW.CA>
 To: vanagon@GERRY.VANAGON.COM 
 Sent: Friday, June 30, 2017 6:14 PM
 Subject: Re: Ideas to stop battery terminal corrosion?
   
Vaseline works for me 

Alistair

> On Jun 30, 2017, at 5:35 PM, Poppie Jagersand <poppie.jagersand@YAHOO.CA> wrote:
> 
> I have a 100Ah deep cycle battery that grows heavy corrosion at the terminals every few months, but is otherwise good.
> 
> Anyone have ideas to stop or reduce the corrosion?
> Would putting a bead of silicone or other sealer at the bottom of the battery terminal posts work?
> Thanks,Martin (82 and 85 Westies)