Red oil light on while driving?
That's a pressure warning, not a service reminder. Pull over somewhere safe and switch off straight away. Don't drive on with it lit: an engine can damage itself within a short distance without oil pressure. Once it has cooled, check the level. Oil pressure warning light goes through what to do next.
What does an oil change involve?
The mechanic drains the old oil, replaces the filter, refills the engine with the right oil, checks the level, looks for leaks and resets the service reminder if the car has one. It's one of the simplest jobs on a car, and one that's easy to get wrong with the wrong oil.
Oil does a lot more than keep parts slippery. It carries heat away, cleans out sludge, neutralises acids and helps the piston rings seal. Heat and hard work break it down, while soot and fine metal particles build up in it. That's why old oil can't just be topped up forever.
How often should you change the oil?
Go by your car's schedule first. RACV's rule of thumb, a minor service every 10,000 km to 15,000 km or 12 months, includes the oil and filter. Plenty of cars sit outside that: Toyota keeps the HiLux, Prado and LandCruiser on six months or 10,000 km, for example, because of Australian conditions.
Kilometres aren't the whole picture. Short trips are hard on oil because the engine never fully warms up, so water and other contaminants build up. Frequent trips under about 15 km count as severe use, and that usually means shorter intervals. If your car only does the school run, it needs the oil done on time even if the kilometres look low.
Some modern cars use an oil life monitor to estimate when it's due. Follow the reminder, and the how often to change engine oil guide has more detail.
Oil change, minor service or logbook service?
| Oil change | Minor service | Logbook service | |
|---|---|---|---|
| Oil and filter | Yes | Yes | Yes |
| Brakes, tyres, lights, battery | Only if you ask | Yes, RACV lists these | Yes, as the maker's checklist says |
| Follows the maker's list for that interval | No | Not always | Yes |
| Stamps the logbook | Usually not | Sometimes | Yes |
| Suits | An older car between services | An older car that's due | A car under warranty, or one you'd like to sell well |
Which oil does my car need?
The one in your owner's manual. In a grade such as 5W-30, the number before the W is the winter grade, which describes how the oil flows when it's cold. The second number describes how thick it is at operating temperature. Thicker isn't automatically better, despite what you might hear about hot Australian summers.
The grade is only half of it. Many makers also list a specification, and that can vary by region for the same car. Mazda's CX-5 manual is blunt: use of unsuitable oil may lead to engine damage which is not covered by the Mazda Warranty.
What a good estimate for an oil change shows
- The oil by grade and specification, and how much goes in.
- The filter, and a new sump plug washer where the engine needs one.
- Whether it's only the oil, or the checks in a minor service as well.
- That the service reminder will be reset and the kilometres noted on the invoice.
- That the old oil goes for recycling.
What you can do, and what to leave
You can
- Check the dipstick every few weeks on a cold, level car. Mazda's manual says to inspect the level periodically.
- Top up with the grade and specification your manual lists, a little at a time.
- Don't panic if it uses a bit: Mazda says it's normal for all engines to consume oil in normal driving.
- If you're changing your own oil, never pour the old oil down a drain. Take it to a used oil collection point.
Leave to the mechanic
- Draining the oil from underneath. Never go under a car held up only by a jack, and hot oil burns.
- Tightening the sump plug and filter to the right torque.
- Working out why the level keeps dropping, if it does.
What we'd do
If the car's under warranty, we wouldn't get a stand-alone oil change: we'd do the logbook service and have it stamped. On an older car, we'd stick to the schedule and shorten it if the car does mostly short trips or tows. Either way, we'd ask to see the oil specification on the invoice. It takes ten seconds, and it's the detail that matters most on this job.