How to Change Your Engine Oil and Filter

Changing the oil is the first real maintenance job most people learn, and for good reason: it is well within reach at home, it teaches you to work safely under a car, and it is the single most important thing you can do to make an engine last. Done properly, it is satisfying. Done carelessly, it is messy and occasionally expensive — so this guide leans hard on getting the details right.

Why oil matters so much

Oil does four jobs at once: it lubricates the moving parts so metal does not grind on metal, it carries heat away, it cleans by suspending tiny particles, and it helps seal the gap between the piston rings and the cylinder wall. Over time it degrades and fills with contaminants, which is why it — and the filter that traps the debris — must be renewed on schedule.

What you will need

• The correct grade and quantity of oil for your engine (check the handbook).
• A new oil filter to match, and a new sump-plug washer if your car uses one.
• A socket or spanner for the sump plug, and an oil-filter wrench.
• A drain pan large enough for the full oil capacity, a funnel and rags.
• Axle stands and a jack, or ramps. See essential tools if you are building your kit.

Choosing the right oil

Use the grade your manufacturer specifies — for example a viscosity rating like 5W-30 — and an oil meeting the correct industry and manufacturer standard for your engine. The first number with the "W" describes cold-weather flow; the second describes thickness at operating temperature. Putting in the wrong grade can affect fuel economy and, on some engines, cause real harm. When in doubt, the handbook wins, every time.

The job, step by step

1. Warm the engine for a few minutes so the oil flows freely, then switch off.
2. Raise and support the front of the car on axle stands. Confirm it is stable before going underneath.
3. Position the drain pan under the sump plug. Loosen the plug with a spanner, then finish by hand — keeping inward pressure so it does not drop into the pan — and let the oil drain fully. This takes several minutes.
4. Remove the old filter. It will hold oil, so keep the pan beneath it. Smear a little fresh oil on the new filter's rubber seal, then fit it hand-tight plus the small extra turn the filter specifies — never overtighten.
5. Refit the sump plug with a new washer, to the correct torque. Over-tightening strips the thread; under-tightening leaks.
6. Refill through the filler cap, adding most of the specified quantity, then check the dipstick and top up gradually to the correct mark. Do not overfill.
7. Run the engine for a minute, check underneath for leaks, switch off, wait, and re-check the level. Adjust as needed.

Reading the dipstick correctly

Pull the dipstick, wipe it, reinsert it fully, then pull it again to read. The level should sit between the two marks — ideally near the upper one, never above it. Both too little and too much oil cause problems: too little starves the engine; too much can foam the oil and damage seals. The colour and feel tell a story too — fresh oil is amber and slippery; very dark, gritty oil was overdue.

Disposing of the old oil — this part is the law

Used engine oil must never go down a drain, onto the ground or in the household bin. In the UK you can take it free of charge to a household waste recycling centre that accepts oil; many will take the old filter too. Pour the waste oil into a sealable container — never one that looks like a drink bottle — and keep it capped until you can hand it in. Treat this as part of the job, not an afterthought.

How often?

Follow your car's service schedule rather than a generic figure, as intervals vary widely by engine and oil type. Short trips, lots of cold starts and towing all shorten the safe interval. If you are unsure, changing it a little early never hurt an engine; leaving it far too long routinely shortens one.

Conclusion

An oil change rewards care more than skill. Support the car properly, use the right oil and filter, set the plug and filter to the correct tightness, fill to the mark and dispose of the waste responsibly. Get those right and you have not only saved money — you have done the most valuable thing there is for the long life of the engine, and learnt the safe-working habits every other job under the car depends on.