What You'll Learn
Aussie Conditions
Look, if you've been out bush or just haven't popped the bonnet in a year, your engine bay is probably a mess of red dust, oil grime, and maybe a few dead locusts. This guide is for anyone from the weekend warrior with a dusty Hilux to the bloke with a show car who wants it mint. I'm going to walk you through the exact process I use in my detailing business, tailored for our brutal Aussie summer conditions.
Why Bother Cleaning Under the Bonnet?
The Gear You'll Need
What You'll Need
Preparation: Don't Skip This!
Cool Down
Never, ever spray cold water on a hot engine. You risk cracking the manifold or warping the head. The engine should be cool to the touch, or just slightly warm. If you’ve just driven back from the shops, give it at least an hour.
Remove Loose Debris
Pick out the leaves, twigs, and dead bugs by hand. If you've been off-road, use a vacuum or the leaf blower to get the chunky red dust out before you get it wet and turn it into mud.
Disconnect the Battery (Optional but Recommended)
If you're nervous or working on an older car with dodgy wiring, just pop the negative terminal off. Better safe than sorry.
Cover the Vulnerable Bits
This is the most important step. Wrap the alternator, any exposed air intakes (especially if you have a pod filter), and the fuse box in foil or plastic wrap. Use painter's tape to seal it up.
Check for Openings
Make sure the oil dipstick is pushed in all the way and the oil filler cap is tight. You don't want water in your oil.
While you're here...
The Step-by-Step Clean
Dry Blow Out
Give the whole bay another blast with the leaf blower. Get into the crevices. It’s amazing how much dust hides under the battery tray.
Pre-Rinse (The Gentle Way)
Mist the engine bay with water. Don't use high pressure here. You just want to dampen the surface to help the degreaser work.
Apply Degreaser
Start from the bottom and work your way up. Spray your APC or degreaser liberally over everything. Focus on the greasy areas like the valve covers.
Agitate with Brushes
This is where the magic happens. Use your detailing brushes to work the cleaner into the grime. Do the underside of the bonnet first so the runoff doesn't ruin your finished work below.
Scrub the Heavy Stuff
Use your stiffer brush on the metal parts of the block or any aluminium components that have that white oxidation.
Don't Forget the Bonnet Underside
Often overlooked! Scrub the painted sections and gently wipe down the heat insulation pad if it's there. Be careful not to soak the pad as they can get heavy and sag.
Dwell Time
Let the product sit for about 3-5 minutes. In an Aussie summer, do this in the shade! If the product dries on the engine, it'll leave nasty streaks.
The Careful Rinse
Rinse from the top down. Keep the nozzle moving and don't linger on electrical connectors. Think of it like a gentle shower, not a blast from a fire hose.
Inspect and Repeat
A customer once brought in a Hilux that had been through the Simpson Desert. One pass didn't touch it. If you still see red mud or grease, hit it again while it's wet.
Initial Dry
Use your leaf blower to push all the standing water out of the holes. Pay special attention to spark plug wells and the battery terminals.
Microfibre Wipe Down
Hand-dry the remaining spots with your old microfibres. This prevents water spots, which look terrible on black plastic covers.
Remove Covers
Carefully take off the foil and plastic wrap. Make sure no water trapped on top of the foil drips onto the parts you were trying to protect.
Run the Engine
Reconnect the battery and start the car. Let it idle for 10 minutes. The heat from the engine will evaporate any moisture you missed.
Apply Dressing
While the engine is warm (not hot), mist your water-based dressing over the plastics and rubbers. This is the secret to that 'new car' look.
Level the Dressing
After a few minutes, wipe over the plastics with a clean cloth to remove any excess. You want a satin finish, not a greasy mess.
Professional Secrets
Watch Out
Aftercare and Maintenance
Common Questions I Get Asked
Will I break my car if I get the engine wet?
Can I use dish soap?
What if my car won't start afterwards?
How do I get rid of that 'white crust' on aluminium?
Is steam cleaning better?
Advanced Techniques: The Showroom Finish
My Go-To Kit
Trusted by 50,000+ Aussie car owners
Professional advice for Australian conditions
Products We Recommend
Keep Learning
Ready to level up your car care?
You've got the knowledge—now put it into action. Explore more guides or check out our recommended products.
Get Weekly Car Care Tips
Join 12,000+ Aussie car enthusiasts
Keep Reading
Getting Red Dust and Grime Out of Fabric Seats (Mar 2026)
Fabric seats are absolute magnets for Aussie red dust, spilled coffee, and salt spray. I'll show you how to deep clean them properly without leaving water marks or funky smells behind.
Keeping the Outback Out: Interior Detailing Tips for the Red Dust
Red dust and coastal salt are an absolute nightmare for your car's interior. Here is how I keep cabins looking factory-fresh without spending all weekend on your knees with a vacuum.
Saving Your Fabric Seats From Red Dust and Spills
Fabric seats are absolute magnets for outback dust and beach salt. Here is how to deep clean them properly without soaking the foam or leaving nasty water marks.
Sorting Out Your Door Jambs the Right Way (Mar 2026)
Door jambs are the most neglected part of any car, but in Australia, they're a magnet for red dust and salt spray. Learn how to deep clean and protect them like a pro so they don't rust out or ruin your interior.

