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Choose the right engine oil and filter, know when to top up or change, and avoid the common mistakes that can shorten engine life.
What Engine Oil Does My Car Need?
Use oil that matches your vehicle’s required viscosity grade, specification and (where relevant) manufacturer approval. The correct info is usually printed on the oil filler cap or in the handbook. If in doubt, ask a professional before filling.
- Viscosity (e.g., 0W-20, 5W-30): how thick the oil is when cold/hot.
- Specification: ACEA/API categories and any OEM standards your engine requires.
- Low-SAPS oils: many modern diesels with DPFs require “C” category ACEA oils.
- Capacity: engines vary widely; check the correct fill amount for your specific engine.
- The first number + W: cold-flow performance. Lower = thinner when cold (better cold starts).
- The second number: viscosity at operating temperature. Higher = thicker when hot.
- Modern engines are designed around specific grades; stick to the specified grade unless a manufacturer bulletin says otherwise.
Beyond viscosity, the specification ensures the oil’s chemistry matches your engine’s needs.
- ACEA: common categories include A/B (petrol/diesel), C (catalyst/DPF compatible), and E (heavy-duty).
- API/ILSAC: US-based specs covering performance and emissions standards.
- OEM approvals: some engines require specific approvals; always match the exact requirement where stated.
- DPF-equipped diesels: typically need low-SAPS “C” spec oils to protect the DPF.
Checking & Topping Up Oil
- Warm the engine briefly, then switch off and wait a few minutes for oil to settle.
- Park level. Pull the dipstick, wipe clean, reinsert fully, then check the level against the MIN–MAX marks.
- If low, add a small amount of the correct oil and recheck. Don’t overfill.
- Look for leaks if the level drops quickly or warning lights appear.
- Prepare tools, the correct oil, filter, new sump plug washer (if used), and a drain pan.
- Raise and support the vehicle safely. Remove the filler cap (helps draining), then the sump plug to drain oil.
- Replace the washer/plug to the correct torque.
- Change the filter:
- Spin-on: lightly oil the gasket; hand-tighten per instructions.
- Cartridge: renew O-rings; torque the cap correctly.
- Fill with the correct quantity/spec oil. Start the engine briefly to circulate, then stop and recheck the level and for leaks.
- Dispose of old oil and filters responsibly at a recycling point. Reset the service reminder if applicable.
Safety: work on a cool engine, use stands on level ground, and follow manufacturer procedures.
- Spin-on filters: metal canisters. Do not overtighten; check the old gasket isn’t stuck to the housing.
- Cartridge filters: paper element inside a reusable cap. Replace all O-rings and lubricate lightly.
- Bypass/anti-drainback valves: help protect engines on cold start; quality matters.
- After fitting: run the engine, check for leaks, and recheck the level after a short drive.
Common Symptoms & Likely Causes
| Symptom | Likely Cause | Action |
|---|---|---|
| Oil warning light | Low oil level or pressure issue | Stop safely; check level; investigate leaks or pressure faults |
| Blue exhaust smoke | Oil burning (worn seals/rings, turbo issue) | Monitor consumption; seek diagnosis |
| Milky residue under cap | Condensation from short trips or coolant mixing | If persistent, get a cooling system check |
| Rapid oil loss | Leak from sump plug, filter seal, gasket or cooler | Inspect and repair leak; refill to correct level |
| Metallic glitter in oil | Internal wear | Do not continue driving; arrange inspection |
| Strong oil smell | Spillage on hot surfaces or leak | Clean spillage; locate and fix leak |
Many vehicles need a service indicator reset after an oil change. Procedures vary by model. If not reset, reminders may continue to show even when serviced.
Environmental & Safety Notes
- Used oil is hazardous — store in a sealed container and take to a recycling point.
- Avoid skin contact; wear gloves and eye protection.
- Clean spills immediately; oil can damage rubber components and paint.
- Never overfill — excessive oil can damage catalytic converters and DPFs.
Oil & Filter – FAQs
Follow the vehicle’s service schedule. Many cars are around 12 months or a mileage interval, whichever comes first. Severe use (short trips, heavy loads) may justify shorter intervals.
In an emergency top-up, a small mix is usually better than running low, but aim to use the exact specified grade and spec. Mixing can dilute the required properties.
Detergent additives suspend contaminants, which darkens the oil. That’s normal. Focus on the correct interval and spec rather than colour alone.
Only if the vehicle manufacturer recommends it. Unapproved additives can affect seals and the oil’s chemistry. Frequent correct oil changes are the safest approach.
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