15 Oil Change Mistakes That Quietly Damage Your Engine
Hi, it's Fabio from Honest Ride Parts.
An expensive engine repair rarely starts with something big. It usually starts with something small: a drain plug that was tightened too hard, the wrong oil, or an old filter seal nobody noticed. Then one day the oil light comes on, the engine starts knocking, and a $40 oil change turns into a $4,000 problem.
Whether you change your own oil or pay a shop to do it, here are the mistakes worth knowing about, in the order they usually happen.
Before you start
- 01
Draining the oil completely cold
Cold oil is thick and drains slowly, so more old oil and dirt stay behind. Run the engine for a few minutes first, then turn it off and wait a little. The rule: warm, not burning hot. Oil and exhaust parts right after a highway drive can burn you badly.
- 02
Opening the oil cap without cleaning around it
Dust and road dirt collect around the oil filler cap. Wipe the area clean before you open it, use a clean funnel, and don't leave the opening uncovered while you walk away.
Draining the old oil
- 03
Reusing a worn drain plug washer
Many drain plugs use a small, soft washer that gets pressed flat to make a seal. After a while it gets hard or cracked and starts a slow leak. If your car uses one, replace it. It costs very little.
Shop drain plug washers - 04
Tightening the drain plug too much
This is one of the most expensive do-it-yourself mistakes, especially with aluminum oil pans. Too much force can strip the threads or crack the pan. Follow the torque number in your owner's manual and use a torque wrench if you have one. The plug is there to hold oil in, not to prove how strong you are.
Shop torque wrenches
The oil filter
- 05
Leaving the old filter seal on the engine
Sometimes the old filter's rubber seal sticks to the engine. If you install the new filter on top of it, you get a “double seal,” and when oil pressure builds, it can blow out and dump oil fast. Every time: check that the old seal came off with the old filter, and wipe the surface clean.
- 06
Installing the filter dry, or too tight
Put a thin layer of fresh engine oil on the new filter's rubber seal (not grease). Then tighten it the way the filter's instructions say, usually by hand. Too tight can crush the seal and makes the next oil change a fight.
- 07
Skipping the filter, or buying the cheapest one
The old filter is full of dirty oil and trapped particles. Changing the oil without the filter mixes old dirt into new oil. And filters that look the same inside the box can be very different inside, with different valves, seals, and filter material. Match the part number for your engine. You don't need the most expensive filter, just a reliable one that fits your car's requirements.
Shop oil filters - 08
Putting the wrong O-ring on a cartridge filter
Many newer cars use a cartridge filter inside a plastic or metal housing. These kits sometimes include several O-rings. Use the right one and put it in the correct groove, not on the threads.
Choosing the oil
- 09
Using the wrong thickness (viscosity)
Numbers like 0W-20 or 5W-30 matter. The first number is about cold starts, and the second is about normal engine heat. Modern engines are built for a specific oil. Don't use “thicker oil because it's hot outside” unless your manual allows it. Check your owner's manual and the oil cap.
- 10
Ignoring the oil's certifications
Two bottles can both say 5W-30 and still be different. Look for the standards your car requires, such as API or ILSAC, or your carmaker's own approval. This matters most for turbocharged, direct-injection, and diesel engines. Also buy from a store you trust, because fake and old oil do exist. If the price seems too good to be true, ask why.
Shop motor oil
Filling and checking
- 11
Putting in too much oil
More oil is not more protection. Overfilling can whip the oil into foam, and foamy oil doesn't protect bearings. Add oil a little at a time, stop just before the full amount, then check the dipstick on level ground.
- 12
Not checking the level again after starting the engine
When the engine starts, oil fills the new filter and the level drops. So: run the engine briefly, turn it off, wait a few minutes, and check again on level ground. Wipe the dipstick, push it all the way in, and read it. It takes two minutes.
- 13
Not checking for leaks before you drive away
Let the engine idle for about 30 seconds, turn it off, and look under the car at the drain plug and filter. Some leaks only show up under oil pressure. Your driveway is the place to find them, not 10 miles down the road.
- 14
Leaving off the underbody panel
Those plastic panels under the engine are annoying to remove, but they protect parts from water and road dirt. Put everything back the way you found it.
Between oil changes
- 15
Adding oil instead of changing it
Topping off a low engine is necessary, but it's not the same as an oil change. Over time, oil collects moisture, fuel, carbon, and tiny metal particles, and adding fresh oil on top doesn't remove any of them. Follow the oil change schedule for your car. If you have to add oil often, ask a mechanic to find out why your engine is using it.
This week's quick checklist
A careful oil change is cheap. A rushed one can be the most expensive “savings” you ever make.
Drive safely,
Fabio
Honest Ride Parts
Inspired in part by a video from Truck Truths on YouTube.
This newsletter is general information, not professional mechanical advice. Always follow your owner's manual and the instructions on your parts.
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