Underbody rust protection

[Bullsta]

Hi all. We have been taking the 17 Sport Exceed on various beach trips including Fraser.
As those of you who go off-road would know, sand gets absolutely everywhere through the chassis.
I am after underbody rust protection recommendations as we would like to keep the car long term.
I wash as best as I can with fresh water after beach use but long term I think rust may become an issue?

[littleriver]

found this product/company to be very good ... we also used them for our Council Life Guard 4wd vehicles ...

http://nilrust.com.au/product-details/chemical-rustproofing/

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