---

In this guide is the explanation on why we need to change our 4WD oils, show you the step-by-step processes, and of course some tips and tricks along the way.

Tools You Will Need

• Socket set
• A couple of drip trays
• An oil filter removal tool to suit your vehicle
• For diffs and transmissions, you will need an oil syringe as you are getting oil into hard-to-reach areas
• Safety first: make sure you have the right jacks and jack stands to secure your vehicle

Choosing the Right Oil

You need to get the right grade of oil for your engine and driveline. You can use the Rego Search functionality when searching oil on the Repco website, or you can use rego2oil.com.au to help find the fluids to suit your vehicle.

Not all oils are made the same, so definitely choose to go with the best quality oil that you can afford. The better quality the oil, the longer life your 4WD will have!

When Should I Change My Oil?

One of the biggest killers of a diesel engine is a lack of maintenance and servicing, in particular, a lack of oil changes. If you don’t change your oils, it can lead to a build-up of sludge that creates a lot of wear on moving components and leads to premature failure.

If you want to get 500,000km+ out of your diesel engine, it is very possible if you keep up with your servicing and oil changes.

Your vehicle's owner’s manual has a recommended service interval, which is the bare minimum for engine oil replacement. Common rail diesel engines should have their engine oil changed every 10,000kms at least, and older 4WDs should have their oil changed around every 5,000kms. If you push your 4WDs hard like we do, we recommend changing your oils more frequently.

Diesel engines create more soot, and even more so if the engine is old, and this is why diesel engines will need more frequent engine oil servicing than a standard petrol vehicle. Good quality oil is essential in picking up the soot and contaminants to keep your engine healthy.

How To Change Your Engine Oil

Here’s the full step-by-step guide for changing your engine oil:

STEP 1: Warm Up Your Engine

When oil warms up, it moves a lot easier throughout your engine – just like melting butter – you will get a lot more oil and soot out, and it will drain faster.

Once you have gone for a drive, park your vehicle on level ground. Some IFS 4WDs may be too low to work under, so you may need to safely secure your vehicle on axle stands on the front and rear to work underneath.

STEP 2: Drain Your Oil (Without Making a Mess)

Shauno’s key to success so no oil gets spilt on your concrete floor or driveway is to put your oil pan/drip tray on top of some old drop sheets in case you miss.

You can let the oil drain into the pan for as long as you like. However, if you have an engine like a modern Ford Ranger or Mazda BT50 with that 3.2L engine, it is advised that you do not let it drain for more than 10 minutes or else the vehicle won’t be able to prime itself. If in doubt, check your owner’s manual.

STEP 3: Remove Old Oil Filter and Fit New Filter

This is potentially the messiest part of the job, so make sure you have your new oil filter and the filter removal tool that suits your vehicle at the ready to do the job nice and quick.

Keep the drip tray under the filter so oil doesn’t leak all over the ground when you take the filter off.

There is a lot of oil in this old filter still, so to help make less of a clean-up job, just put the dirty filter in the box of your new filter.

A common mistake made by 79 series owners is when removing the old filter, when pulled out too hard, it can remove the internal metal rod, which when removed will cause the new filter to collapse and will not let any oil into your engine – so make sure the metal rod is still there when you remove your filter.

Throw away your old O-ring, and give your new O-ring, which came with your filter, a light coating of oil as this will help create a nice seal and make it easier to put on. Once lightly coated, make sure you put the new O-ring into the right groove, put the new filter on and then it is ready to install.

STEP 4: Fill It Up!

Now it is time to fill your engine oil back up, but first, you should double-check your sump plug and new filter are back in, as the last thing you want is to drain brand new oil onto your shed floor.

Have a rag at the ready for any spills and move your drip tray and drop sheet to underneath where you fill your oil from just in case you spill any oil.

A nice little tip when filling from a full and large bottle of oil is to pour from the side to reduce glugging, and create a steadier stream of oil. A funnel also makes life easier!

This engine takes 9.5L worth of oil, so it gives a good indication of how much oil you need to buy, and that we will need to use almost all our 10L bottle. Bottles of Castrol oil have volume markers on the side to know how much you have poured in. Make sure you check how much oil your engine needs, so you are prepared!

Check your dipstick, then run your vehicle for a few minutes, and check again as sometimes your filter may need to fill up with oil as well. Then you are all done!

Differential and Transfer Case Oil

Water in your differential oil can over time kill your diff. This water ingress can easily happen from river crossing and driving through deep bog holes.

The drain plug is always at the lowest point of your differential, and the top plug is your fill point. Taking both plugs out when draining will make it flow faster and make it an easier job.

A little tip is to always undo the filler plug first, this is just in case this plug is hard to undo, or you may round the bolt. If you drained the oil then cannot undo your filler plug, then you are left stranded and unable to drive as you can’t refill your oil.

Once your filler plug is off, you can dip in your finger to inspect how full your diff oil is, and even inspect the quality of the oil.

When Should You Change Your Diff Oil?

The recommended servicing interval is normally every 20,000kms, but if you drive your 4WD hard, through mud and water, then we suggest about every 10,000kms.

Milky diff oil means water/mud ingress into your oil and definitely means it is time to change your differential oil.

Worn Diff Gears

When you remove your diff drain plug, inspect the plug for any little bits of metal as it has a magnetic end. This is a sign that your differential gears are worn.

Limited Slip Differential (LSD)

For the rear diff, you need to work out if you have an LSD, and this information can be found in your owner’s manual. This is because you need a different grade of oil (LSD Suited Oil) if you have or don’t have an LSD.

Manual Gearbox Oil

Draining your manual gearbox is the same process as your differential. You want to check for metal pieces too on the end of the magnetic drain plug to check the heath of your gears. Seek repairs if you find a stack of metal shavings and chips as this means something inside is not right.

Do not overtighten your drain plugs when fitting them back on as it is not essential and will make your next service a bit easier.

For the manual gearbox and 4WD transfer case, we used Castrol Universal 80W-90 gear oil for superior gear shift performance over a wide temperature range – particularly cold shift performance.

Filling Your Gearbox and Transfer Case Oil

Again, this is essentially the same as your differentials. Put the drain plug back in, remove the filler plug and use an oil syringe to fill it up. Once oil starts trickling back out the filler hole, it is now full and you can put the filler plug back.

Automatic Transmissions

Draining your auto transmission is much more involved and it is best to get an approved workshop to do it for you.

This is because there are many different types of automatic transmissions, and they require a power flush to remove the old and dirty oil from the entire system. Draining from the sump alone will only remove half the contents at best.

Check the old automatic transmission oil for colour and smell. If it looks dark and smells burnt, chances are your transmission has been getting too hot, and you may need to install a bigger oil cooler.

What To Do With Old Oil

Our tip is to fill up your old empty oil cans/bottles and write on the in permanent marker “OLD OIL” and dispose of them at your local tip or local oil recycle drop offs.

The Best Maintenance is at Home

Now you are all done, time to clean up your shed and your tools. It is so easy and cheap to be able to service your 4WD’s oils at home and gives you a sense of satisfaction too!

You don’t need to be a mechanic to tackle these jobs and doing it at home will have your 4WD and your bank account thanking you!