When to Change Your Engine Oil

Engine oil is your car's lifeblood. Get the intervals wrong, and you could be facing expensive engine damage. Here's everything you need to know about when to change your oil.

You've probably heard "change your oil every 6 months or 6,000 miles." This used to be standard advice, but it's outdated for modern vehicles. Today's engines and oils are far more advanced.

Most modern cars using fully synthetic oil can go:

• ▸**12 months or 10,000-12,000 miles** for petrol engines
• ▸**12 months or 12,000-15,000 miles** for diesel engines

However, this depends on:

• ▸Your car manufacturer's recommendations (always check your handbook)
• ▸The type of oil you use (synthetic vs semi-synthetic)
• ▸Your driving conditions

You should change your oil more often if you:

Do lots of short journeys - Engine never fully warms up - Oil doesn't reach optimal working temperature - More condensation builds up in the oil - Increase frequency by 30-50%

Drive in dusty conditions - More particles enter the engine - Oil filter gets clogged faster - Consider 6-month intervals

Tow heavy loads - Engine works harder and gets hotter - Oil breaks down faster - Follow "severe duty" schedule in handbook

Do mostly city driving - Lots of stop-start driving - Engine rarely operates at optimal temperature - More wear on engine components

Use your car for business (high mileage) - Rack up miles quickly - Stick to mileage-based intervals rather than time

Engine oil does several critical jobs:

Lubrication Prevents metal-on-metal contact between moving parts. Without it, your engine would seize in minutes.

Cooling Carries heat away from the combustion chamber and moving parts. Oil can be 200°C+ during normal operation.

Cleaning Picks up dirt, metal particles, and combustion by-products. That's why used oil is black - it's doing its job.

Sealing Helps piston rings seal against cylinder walls, maintaining compression and efficiency.

Protection from corrosion Modern oils contain additives that protect against rust and corrosion, especially important if the car sits unused.

After 12-18 months without change: - Oil becomes thicker and sludgy - Reduced flow means less cooling - Increased engine wear - Reduced fuel economy

After 18-24 months: - Significant sludge buildup - Oil passages can become blocked - Potential oil pressure problems - Risk of catastrophic engine failure

Long-term neglect: - Complete engine failure - Repair costs of £3,000-£8,000+ - Possible scrap vehicle

I've seen engines with 30,000 miles that are worn like 150,000-mile engines, all due to neglected oil changes.

Between services, check your oil level monthly:

1. Park on level ground 2. Wait 5 minutes after switching off 3. Remove dipstick and wipe clean 4. Reinsert fully and remove again 5. Check level is between MIN and MAX marks

If it's low, top up with the correct grade of oil. If you're losing oil between services, there's a problem that needs checking.

Some manufacturers claim sealed gearboxes with "lifetime" oil. In reality:

• ▸"Lifetime" often means warranty period (3-5 years)
• ▸Oil degrades regardless of marketing claims
• ▸Changing gearbox oil can prevent expensive failures
• ▸I recommend gearbox oil change every 60,000 miles

Always use the specification in your handbook. Key factors:

Viscosity Grade (e.g. 5W-30) - First number = cold flow properties - Second number = high temperature viscosity - Wrong grade can cause engine damage

Specification (e.g. VW 504.00) - Manufacturer's specific requirements - Ensures compatibility with your engine - Using wrong spec can void warranty

Quality (Fully Synthetic vs Semi-Synthetic) - Fully synthetic lasts longer - Better cold start protection - Superior high-temperature performance - Worth the extra cost

When you book an oil change with me:

• ▸I check your handbook for correct specification
• ▸Use quality oils (Castrol or equivalent)
• ▸Replace oil filter
• ▸Check for leaks
• ▸Reset service indicator if needed
• ▸Dispose of old oil properly (it's illegal to pour it down drains)

Basic oil service from £60 including oil and filter for most cars.

For most drivers: - Change oil every 12 months or 10,000 miles - More often if you do lots of short trips - Always use the correct specification - Check level monthly

Oil changes are the single most important maintenance task for your engine's longevity. A £60 oil change every year prevents a £5,000 engine rebuild.

Don't gamble with your engine - stick to regular oil changes and it'll easily last 200,000 miles+.