10 Major Mistakes You're Making When Changing Your Car Oil

If you change your own oil (or even if you have a shop do it), your car may not be getting all the attention it needs. Almost everyone who has ever changed the oil in a car has made at least one of these mistakes at one time or another. To help you learn from our mistakes (and so that you don’t have to make them yourself), here is our list of the top ten major mistakes you’re making when changing your car's oil.

Usually when you get your oil changed at a shop they will place a sticker on your windshield telling you when the oil was last changed. The sticker acts as a reminder, and lets you know when the next oil change is due. If you are changing your own oil, remember to keep track of the mileage and date, so you know when it’s time to do the next service. Otherwise, you’ll be trying to remember the exact date and mileage of your last change, or you may forget to do your oil change altogether.

Oil changes often coincide with the tire manufacturers’ recommended tire rotation schedule (usually somewhere between 5,000 and 10,000 miles). Rotating your tires every oil change can be quite a bit of work (especially if you don’t have a lift), but should help them wear more evenly and last longer.

On some cars, especially those designed in European countries, the oil drain plug will use a soft metal washer to seal it. These washers are often not reusable because they are crushed the first time the drain plug is tightened down. If you don’t replace the washer, you may end up with a slow and annoying leak. If your car uses a replaceable oil filter cartridge instead of a normal filter, you might want to consider changing the oil filter cover o-ring at every oil change as well.

Some people seem to really like to tighten things as much as they possibly can, even when there is no reason to. Tightening a clean new oil filter with one hand is usually enough, and makes removing it much easier (you might not even need to use a wrench, sometimes just two hands are enough). For the drain plug, if it doesn’t have a crush gasket, 20 to 25 ft-lbs is usually about right, while plugs with crush washers are usually tightened a bit more, around 30 to 35 ft-lbs. Overtightening will just cause you problems when it comes time to remove the filter or drain plug.

If your owner’s manual recommends synthetic oil, you should follow the recommendation, but otherwise using synthetic might be just a waste of money. Unless your car sees severe duty such as extreme engine temperatures (some turbocharged and supercharged vehicles fall into this category, as well as some high performance naturally aspirated engines), towing, or racing, conventional oil might be the right choice for you. Synthetic is not recommended for use in some engines, for example in rotary engines where it can damage seals unless specific care is taken to choose a compatible synthetic oil.

If you are still using 10w30 because that’s what you’ve always used or because that’s what you remember your mother or father buying, you’re probably making this mistake. Modern cars have tighter tolerances, and aren’t usually designed to use 10w30 anymore. Today, the most common weight is 5w30, though check your owner’s manual and use what is specified. Many cars are switching to even lighter oils like 5w20 and 0w20. Some exotic cars use hard to find weights such as 5w50. Not using the right oil weight could increase engine wear, cause engine damage, or decrease fuel economy.

With today’s oils and engines, using an oil additive is probably not going to provide any benefits, and may in some extreme cases actually harm your engine. Generally, if your motor is in good shape, and you follow the recommended oil change interval and use the recommended type and weight of oil, using an oil additive is just going to be a waste of money. Today’s engines often outlive the vehicles that they are installed in, even without the use of any special additives.

If you bring your car into a shop for an oil change, they’ll probably want to do a lube job, grease your doors, grease your emergency brake, and check the air filter, brake fluid, transmission fluid, engine coolant, and power steering fluid. Many times people who do their own maintenance will call it a day as soon as they are done swapping out the oil, without tending to these other tasks. While many cars today don’t come with any grease fittings that need servicing, some aftermarket parts still include grease zerks that should be kept filled with a good quality grease.

The recommendation used to be to check your oil every time you filled your car up with gas. Some full-service stations (remember those?) even offered to check your oil for you, and if the attendant forgot to offer, your gas was free. Today you are probably safe checking your oil once every week or two, unless you know your car burns oil or has a leak. Some people are pedants and recommend checking it every day, which seems excessive, but better safe than sorry, right?

It’s best to follow the oil change interval specified in your owner’s manual. If most of your driving is stop and go, you spend a lot of time idling, you tow regularly, or you live on a dirt road, you may need to follow the ‘Severe’ oil change schedule. While changing the oil too frequently probably isn’t going to damage your engine, it is going to hurt your wallet. Not changing the oil frequently enough on the other hand can lead to costly engine repairs and the dreaded ‘sludge’.