As an automotive technician, I get questions about synthetic oil – “Is it better? Can I go further with it? Can I mix it with regular oil?” – on a relatively regular basis. For the record, here’s what synthetic oil is all about.
What makes synthetic oil different
It is more stable
It lasts longer
It improves your fuel consumption
Switching from conventional to synthetic
As the name indicates, synthetic oil isn’t refined from centuries of mashed dinosaurs like regular mineral oil. Rather than refining crude oil, it is created through what is called the Fischer-Tropsch process. I won’t get too Bill Nye on you with this, but basically it is created from a base of carbon monoxide and hydrogen. The end result of this chemical process is a synthetic lubricant capable of every task previously managed by that old dino-juice, but with a slightly elevated cost and a handful of interesting bonus features. “Is it better?” Absolutely yes.
One of the challenges faced by conventional mineral oils is temperature stability. It has a finite operating range and in a climate like Canada where temperatures can drop below minus 30 degrees Celsius, conventional oils often aren’t able to keep things properly lubricated through those first few seconds of engine operation. A few seconds may not sound like a big deal, but any amount of metal scraping against metal without proper lubrication is never a good thing. That stability is occasionally relevant when it comes to noisy engines on cold-start. If you’re running conventional oil and you notice a whole lot of ticking noise from the top end of your engine for the first minute or two it is quite possible the hydraulic lifters are sticking due to poor lubrication. Before condemning them all in an expensive repair, a transition to synthetic oil may have a slim chance of remedying the situation.
The whole point of engine oil, aside from lubrication, is to trap any particulate matter, to keep it from clogging things up or damaging your engine. The reason engine oil is changed is that it has a limited amount of space to trap these particles, and oil producers have translated that space into a mileage calculation. Because of synthetic oil’s different molecular structure, it has a greater ability to trap these particles, which means, although it’s costing you more up front, it is lasting a lot longer in between changes. Depending on the oil manufacturer, you could be going up to three or four times further on an oil change by running synthetic oil. If you do the math, suddenly the costs of one or the other aren’t that far apart.
Now I know you may be thinking this argument is all marketing spin, and part of me wants to agree with you. A few years back a sergeant from the Windsor, Ontario police force in charge of fleet logistics performed his own series of real-world testing and was quick to claim that most fuel consumption claims related to fluids were bunk. Unfortunately Sgt. William Hunt Jr. failed to realize that real-world conditions are never grounds for good science. Instead, I’m much quicker to believe the dozens of tuners across the world that have done back-to-back comparisons on a rolling dynamometer and quickly found at least small improvements when switching to synthetic engine, transmission, and gear oils. We are talking about improvements of only about two to six percent, but even two percent means using 200 fewer litres over 10,000 kms if you’re already averaging 10 L/100 km. You likely won’t see much of a tank-to-tank gain, but as you can see it will add up over time.
I’ve heard many technicians claim you shouldn’t switch a car from conventional to synthetic oil because it will cause oil leaks. In the early years of synthetics, back in the ’70s, there were a handful of issues regarding leakage, but to put it simply that just isn’t a point of concern any more. If something starts to leak after changing oils, odds are it would have started leaking one way or another. As long as your gaskets and seals are in decent order, 5W30 oil is 5W30 oil regardless of composition, so if you need to toss in a litre of synthetic into your conventional-oiled engine, there’s no need to lose sleep about it.