Which matters more: time or distance?
It's a topic tailor-made for water-cooler debates: which should you follow for vehicle maintenance and inspections: time or distance? All automaker recommendations list both with three months of time equating to about 5,000 kilometres, on average. However, most have drastically extended their maintenance intervals over the past decade or so, and few actually list the need for any services after just three months of use.
However, this discussion has become more important lately. Natural Resources Canada pegs our average driving distance at just over 15,000 kilometres annually, but given the COVID-19 pandemic, we have seen personal vehicle use drop dramatically. It may be some time before we return to normal commuting distances if ever.
So, let's look at common vehicle maintenance items to see whether time or distance is the major factor.
ENGINE OIL AND FILTERS
The need to replace engine oil is based on its contamination from living in an internal combustion engine. While it's primarily a distance-based need, time plays a factor as well. When engines idle to warm up, they aren't collecting any distance, but the oil is getting a workout nonetheless. And short runs in colder weather — typical pandemic-season driving — can be the hardest type of driving on oil, because it can lead to condensation contamination, which happens when water accumulates in the oil thanks to engines that don't reach full operating temperatures.
If your automaker's recommendation will let you drive a year's worth of your distance, go ahead, but check the oil regularly and look for signs of water contamination. This will usually appear as a coffee-with-cream-coloured, pudding-like buildup on the underside of the oil-fill cap.
BRAKES AND SUSPENSION
Unless you're doing way more than 15,000 kilometres per year, you can relegate these items to a once-a-year checkover. For high-milers, follow the automaker's advice with regards to distance, but be prepared to figure out if wear items such as brake linings will make it to your next annual inspection.
Also note that brake pads don't wear evenly over their lifetime; as they get thinner, they lose some ability to resist overheating, making their second half of life roll by quicker than the first.
Brake and suspension inspections should be more than a visual check. Caliper sliders and suspension components need to be exercised to check if cleaning and lubrication is needed. And you'll never see heat cracks in brake pads unless you remove them.