Most folks hear *marine grade* and immediately think boats. Salt spray, barnacles, maybe a bloke named Dazza drinking a beer on the deck. But if you're building or modifying a 4WD — especially if you’re on the Sunshine Coast where mud, salt, sand, and storms are just part of life — SS316 fasteners might be the smartest decision you make since switching from an esky to a fridge slide.

Let’s talk about where marine-grade fasteners belong *off* the water — right in your garage, and more importantly, all over your rig.

Why SS316 Isn’t Just for Boats

Let’s clear something up. Not all stainless steel is made equal. The hardware aisle at the local big box store might slap *"stainless"* on the label, but that doesn’t mean it’ll hold up to Queensland's coast, let alone 50,000km of corrugated roads and salty beach crossings.

SS316 — aka marine grade stainless steel — is the good stuff. It’s got molybdenum (say that five times fast) in the mix, which gives it superior corrosion resistance, especially in chloride-heavy environments like… yep, saltwater. Or beach air. Or muddy creek beds. Or the undercarriage of a 4WD that’s spent a weekend at Double Island Point.

While SS304 might be okay for indoor use or a kitchen shelf, when you’re wrenching on a custom dual battery tray, a drawer system, or that rear bar you made from scratch, SS316 will outlast just about anything else — and it won’t seize up or corrode into a flaky mess when you need to take it apart in five years.

Where SS316 Fasteners Make Sense on Your 4WD

You don’t need to go full stainless on your whole build (unless you like to show off or have deep pockets), but there are key places where marine grade fasteners make life easier and future-proof your setup.

1. Underbody and Suspension Components

Anything underneath your 4WD is getting hammered by water, mud, salt, and rocks — especially if you're doing serious off-roading up Cooloola or Fraser. Swapping out factory bolts or installing aftermarket bash plates, diff drop kits, or lift kits? SS316 bolts, washers and nylocs can keep everything secure without rusting solid.

High tensile fasteners like Grade 12.9 or 10.9 are often used for load-bearing jobs (and for good reason), but for parts that aren’t taking drivetrain torque — like guards, trays, and brackets — SS316 is a worthy upgrade for corrosion resistance. For mixed jobs, you can always go zinc-coated high tensile and hit them with a dab of anti-seize, but you’ll still be under there scrubbing rust stains one day. Stainless stays clean.

2. Electrical and Battery Mounts

Nothing ruins a dual battery setup quicker than corrosion. SS316 bolts, nuts and washers are perfect for mounting battery trays, inverters, fuse blocks, and even solar brackets. Combine them with nylon insulating washers if you're worried about electrical conductivity, and you'll have a tidy, safe, and rust-free setup.

It’s also worth noting that stainless steel nuts and bolts won’t bite into terminals like some of the softer metals, which helps you avoid voltage drop issues over time — or worse, a melted lug when you’re 600km from the nearest servo.

3. Roof Racks, Canopies, and External Mounts

If you’ve ever seen rust streaks coming from a roof rack bolt, you know the pain. Your canopy, ladder mounts, awning brackets, and light bar fittings are all prime candidates for SS316. They live in the elements full-time — UV, salt air, dust storms, the occasional wayward magpie — and they’re usually overlooked until you try to unbolt something and the head snaps clean off.

Use stainless washers to spread the load, nyloc nuts to prevent vibration, and don’t forget some marine grease or anti-seize paste so you can undo them later without reaching for the grinder.

Are Stainless Fasteners Strong Enough?

Here’s where people get twitchy: “But aren’t stainless bolts weaker than high-tensile?”

Yes — and no. SS316 fasteners aren’t made to replace high tensile bolts in structural or high-load applications. We wouldn’t recommend them for suspension arms or engine mounts. But in areas where corrosion is the bigger enemy — not shear force — stainless wins every time.

It’s about using the right bolt for the right job. And if you’re not sure, that’s what we’re here for. We’ve got decades of experience under the hood (and under the chassis), and we’re more than happy to steer you in the right direction.

Think of stainless fasteners Sunshine Coast style: made for our environment. Wet, wild, and salty.

SS316 vs Galvanised: Why It’s Worth It

Now, let’s address the elephant in the shed — cost.

Yes, SS316 nuts and bolts will cost you more upfront than galvanised or zinc-coated fasteners. But here’s what you don’t get with stainless: flaking coatings, rust stains, seized threads, and Saturday afternoons spent replacing parts that should’ve lasted years.

Gal fasteners are fine… until they’re not. Once the coating wears off, it’s game over. In contrast, marine-grade stainless fasteners keep performing year after year, no matter the punishment.

So if you're planning to keep your rig for the long haul — or just hate doing the same job twice — stainless is worth every cent. 

Final Word: Bolt It Right, First Time

Whether you’re mounting recovery points, wiring up a canopy fit-out, or building a custom drawer system, using the right fastener is half the battle. And when corrosion is part of the equation — which, around here, it always is — SS316 stainless steel fasteners are your best mate in the garage.

At Bolt-In Co Sunshine Coast, we stock a huge range of marine grade fasteners, SS316 nuts and bolts, and high-quality stainless fittings for just about any 4WD application you can dream up. We’re based right here in Maroochydore, and we ship Australia-wide — from the Top End to Tassie.

If you’re not sure what fastener you need, swing by the shop or give us a ring. We’ll sort you out. No guesswork, no gimmicks — just good, solid gear that won’t let you down.