Whether you’re a do-it-yourselfer and handle your own oil changes — or have this messy, not-fun job handled by a service shop — it’s important to know when to change, why to change, and what to watch out for:
When should you change your oil? This varies from vehicle to vehicle, and manufacturer to manufacturer, but the owner’s manual that came with your specific car or truck is what you should always pay attention to. You’ll probably find there’s a schedule for “normal” as well as “severe” service. Many people assume that since they just drive to and from the office, they fall into the “normal” category and the extended mileage/time interval listed. But this is often not the case. In fact, unless you live in a rural area and drive your vehicle at highway speeds regularly and for at least 15-20 minutes at a stretch, in all likelihood you fall into the “severe” category. And that means more frequent oil/filter changes — as frequently as every three to four months or every 3,000 miles if you do a lot of stop-and-go city-type driving.
Believe it or not, the same is also true of lightly used vehicles that only go out once or twice a week or sit for extended periods of time. Condensation, unburned fuel, and other contaminants quickly foul the oil, reducing its ability to protect against wear and tear. And it should go without saying that if you beat on your car — hard driving, frequent “dragstrip-style” full-throttle starts, etc. — you’ll also likely need to adopt a more aggressive oil-change regimen.
However, all those standard rules come with a catch. Many new cars now come with oil-life reminders that gauge the quality of the remaining oil in your car--and can predict when it needs to be changed. As a result, service intervals have grown longer--and your car now can tell you when it actually needs an oil change.
If you have any doubts about which service schedule to adhere to, ask at your dealer. The service advisor will ask you detailed questions about how you use your vehicle and based on this, help you to decide what’s right for you and your vehicle.
Why does oil need to be changed? Believe it or not, oil does not “wear out.” In fact, it can be recycled and re-used again and again. What does wear out — or get used up, at any rate — is the additive package that’s mixed into each quart of oil when it is manufactured and bottled. These additives help keep internal engine parts clean and free of build-up (sludge, carbon deposits, varnish, etc.). Once these additives are used up, there’s no longer anything to keep the gunk at bay. And while the oil itself isn’t used up, it eventually maxes out its ability to hold contaminants and dirt particles in suspension, away from delicate moving parts. That means increased friction and accelerated wear and tear. Saving $30 every year by putting off an oil change for a couple of months could cost you a great deal more in the long run, in the form of a worn-out engine that’s ready for the salvage yard years before its time.
As for the type of oil you use, these days it’s more important than ever to find out exactly what service rating and viscosity your engine needs to keep it running as designed. Fuel economy and emissions output can be affected negatively by using oil that is too thick, while failure to use oil that meets the manufacturer’s specifications for protection can void your warranty and leave you holding the bag for expensive repairs. If you do your own oil changes, it is critical to keep receipts showing the type of oil (and filter!) you used, so that if there is a lubrication-related failure down the road, the manufacture can’t lay the blame (and the bill) at your feet for using the wrong stuff.
Always re-check the level on the dipstick yourself after having the oil changed. It is not at all uncommon for Quick-Lube places to leave you a little (or even a lot) low. Unlike the do-it-yourselfer who puts oil in quart by quart, these shops use a hose connected to a large barrel and pump the (supposedly) appropriate amount in. But sometimes, they get it wrong. Either they don’t realize the pump didn’t put as much in as it should have or they didn’t dial up enough because they didn’t check the service manual and thought you only needed four quarts when in fact, your engine needs five. Never assume the shop got it right, even if it’s a dealer. People make mistakes; things happen. The thing to bear in mind is that running an engine without enough oil in it can be catastrophic — and you don’t want to be haggling in the aftermath about who is going to be paying $4000 to replace your burnt-out engine over a couple of bucks of motor oil.
You should also re-check the oil level at least every two weeks (when cold, after the engine has been sitting overnight, ideally) and top it off as necessary. One of the nicer things about new cars is that while they can be more difficult to service, usually things like the oil dipstick are more readily accessible and easy to check. Your owner’s manual will tell you where to look if you don’t know where the dipstick is — as well as tell you how to read it. Just like periodically checking the air pressure in your tires, this is important self-service that anyone can — and everyone should — learn how to do, and do regularly.