Your Guide to a Spot-On DIY Oil & Filter Change

Performing an oil and oil filter change is arguably one of the most fundamental and rewarding maintenance tasks any car owner can undertake. Not only does it offer significant savings compared to garage costs, but it also provides an invaluable opportunity to get to know your vehicle better. For many, it’s a rite of passage into proper car care, ensuring the longevity and smooth running of your engine. This comprehensive guide, drawing on decades of experience, will walk you through every step, from preparing your workspace to safely disposing of the old oil, ensuring your beloved motor remains in tip-top condition.

The Unsung Hero: Why Regular Oil Changes Matter

Your engine oil isn't just a lubricant; it's a multi-tasking fluid that plays several vital roles in the health and performance of your car's engine. It lubricates moving parts to reduce friction and wear, helps dissipate heat, keeps the engine clean by suspending contaminants, and provides a seal between the piston rings and cylinder walls. Over time, engine oil breaks down due to heat and contamination from combustion by-products, leading to a reduction in its protective qualities. A clogged oil filter, meanwhile, can no longer effectively trap harmful particles, allowing them to circulate and cause accelerated wear.

Regular oil and filter changes are the cornerstone of preventative maintenance, ensuring your engine remains well-protected, efficient, and reliable. Neglecting this simple task can lead to decreased fuel economy, reduced performance, and, in severe cases, costly engine damage. Think of it as your car's lifeblood; keeping it fresh is paramount.

Preparation and Paramount Safety

Before you even think about cracking open a spanner, meticulous preparation and an unwavering commitment to safety are non-negotiable. Working under a car carries inherent risks, and taking shortcuts can lead to serious injury.

Essential Tools You'll Need:

• A suitable container or oil drain pan large enough to hold all the old oil (typically 4-7 litres, but check your car's manual). An MGB, for example, holds around seven pints, so ensure your container can accommodate this volume.
• Socket or spanner set for the sump plug.
• An oil filter wrench or a special grab tool if your filter is too tight to remove by hand.
• Funnel for refilling the new oil.
• Torque wrench (recommended for re-tightening the sump plug to specification).
• Clean rags or shop towels.
• New engine oil (correct type and viscosity for your vehicle).
• New oil filter (ensure it's the correct one for your make and model).
• New copper washer for the sump plug (often supplied with the filter or sump plug, but always worth having a spare).
• Safety glasses and work gloves.
• Axle stands, car ramps, or a hydraulic lift.

Safety First, Always:

Never, ever work under a car supported solely by a jack. Jacks are designed for lifting, not for supporting a vehicle for extended periods. Always use sturdy axle stands placed on a firm, level surface. If using ramps, ensure they are securely positioned and the car is driven onto them slowly and carefully, with the handbrake applied and wheels chocked. If you're fortunate enough to have access to a post lift, ensure it's operated correctly and the vehicle is securely positioned. Always wear safety glasses to protect your eyes from drips and debris, and gloves to protect your hands from hot oil and chemicals.

Getting Underneath: Raising Your Vehicle Safely

The first step in a successful oil change is to gain safe and convenient access to the underside of your car. This usually means raising it. While a professional post lift provides the ultimate working height and convenience, most DIY enthusiasts will rely on sturdy car ramps or axle stands.

If using ramps, drive your car slowly and carefully onto them, ensuring the wheels are centred and the vehicle is fully on the flat part of the ramp. Engage the handbrake and place chocks behind the rear wheels. If using axle stands, first lift the car with a hydraulic jack at the manufacturer-specified jacking points. Once raised, carefully place the axle stands under strong points of the chassis or subframe, ensuring they are stable and on firm, level ground. Gently lower the car onto the stands, giving it a slight wobble to confirm stability before you crawl underneath. Never work on a vehicle that isn't absolutely secure.

Draining the Old Oil: The Messy Bit

With the car safely elevated, locate the sump plug, usually found at the lowest point of the engine's oil pan (sump). It's generally a large bolt, often hexagonal or square. Before you remove it, position your large oil drain pan directly underneath. It's a good idea to have the engine slightly warm, as warm oil drains more easily, but not scalding hot, which could cause burns.

Using the correct size socket or spanner, carefully loosen and then remove the sump plug. Be prepared for the oil to gush out once the plug is free. Allow ample time for all the old oil to drain completely. This can take anywhere from 10 to 20 minutes, depending on the oil's viscosity and temperature. An MGB, for example, holds approximately seven pints (just under 4 litres) of oil, so ensure your container is adequately sized to prevent spills.

Once the flow has reduced to a slow drip, clean the area around the sump plug hole. Crucially, replace the sump plug with a new copper washer. These washers are designed to crush and create a perfect seal; they can deteriorate over time and should always be replaced to prevent leaks. Tighten the sump plug firmly, ideally to the manufacturer's specified torque setting using a torque wrench. Over-tightening can strip the threads, while under-tightening will lead to leaks.

An Opportunistic Inspection: While You're Underneath

While your car is still elevated and the old oil is draining, seize this valuable opportunity to conduct a quick visual inspection of other components underneath. This is a common practice for experienced mechanics like Roger Taylor, who often advises looking at the gearbox drain nut and checking the oil level in the rear differential. Ensure the gearbox drain nut (which could be either hexagonal or square) is tight. When checking the differential oil, remember never to overfill. Also, inspect the breather on the rear axle for any signs of corrosion or blockage, as a blocked breather can lead to pressure build-up.

This quick scan can help you identify potential issues before they become major problems, highlighting the true value of DIY maintenance beyond just the immediate task.

Removing and Replacing the Oil Filter

Next, turn your attention to the oil filter. Its location varies significantly between vehicles; it might be a spin-on canister filter or a cartridge filter housed within a permanent casing. While still underneath the car, check that the oil filter holder's securing nut (if applicable) is tight in position.

Place a small tray or some rags directly beneath the filter before you begin to unscrew it, as a small amount of residual oil will inevitably run out. The oil filter should only be hand-tight from its previous installation. If it doesn't budge by hand, you'll need an oil filter wrench or a special grab tool to gain leverage. Be careful not to crush the filter with the tool if it's a spin-on type. Once loose, carefully unscrew the filter, allowing any remaining oil to drain into your tray.

Before fitting the new filter, take a moment to clean the filter mounting surface on the engine block. Crucially, apply a thin film of new engine oil to the rubber seal on the new filter. This lubricates the seal, helping it to seat properly and prevent tearing during installation, ensuring a good seal. Screw the new filter on by hand until it's snug, then give it another half to three-quarters of a turn. Never over-tighten an oil filter with a wrench, as this can damage the filter or the engine block, making future removal difficult and potentially causing leaks.

Refilling with Fresh Oil: The Right Choice

Now that the old oil is drained and a new filter is in place, it’s time for the fresh, golden fluid. This is where choosing the correct type of oil becomes paramount, especially for older engines. While modern synthetic oils offer superior performance and longevity for contemporary vehicles, they can sometimes cause issues with older engine designs. Roger Taylor, for instance, strongly recommends using 20/50 Castrol Classic or a Unipart mineral-based oil for vintage cars like the MGB, advising against modern synthetic oils which can harm older engines due to their different additive packages and detergents.

Understanding Oil Types: Mineral vs. Synthetic

Always consult your car's owner's manual for the recommended oil type and viscosity. Use a clean funnel to pour the new oil into the engine's oil filler cap opening. Pour slowly to avoid airlocks and spills. Roger advises to always measure accurately the volume of oil you put in. For an MGB, this is seven pints. Do not rely solely on the dipstick during the initial fill, as it is not unknown for cars to have the wrong dipstick, which can give you a false reading.

Once the specified amount of oil is added, replace the oil filler cap. Before dropping the car to the ground, conduct a thorough visual inspection all-round for any signs of leaks, particularly around the sump plug and the new oil filter. Address any leaks immediately.

Final Checks and Responsible Disposal

With the new oil in and the filter secured, lower your car safely back to the ground. Start the engine and let it run for a minute or two. This allows the new oil to circulate and the filter to fill. Check your dashboard for any oil pressure warning lights – if one illuminates, switch off the engine immediately and investigate. Once the engine has run briefly, switch it off and wait a few minutes for the oil to settle in the sump.

Now, perform the final dipstick check. Remove the dipstick, wipe it clean, reinsert it fully, then remove it again to check the oil level. It should be between the 'min' and 'max' marks. If it's low, add small amounts of oil gradually until it reaches the correct level. Be careful not to overfill, as this can cause engine damage.

Finally, remember to check other fluid levels that might be affected or are often overlooked. On an MGB, for example, the gearbox oil level is located under the carpets on the transmission tunnel, just below the dashboard. This can be fiddly to access and check. You will likely need a long tube to top-up the gearbox using the same 20/50 oil you used for the engine, assuming your manual specifies this.

The last, but by no means least important, step is the responsible disposal of your old oil and filter. Never pour used oil down drains or onto the ground. It is a hazardous waste. These can be taken to civic amenity and recycling locations, often run by your local council, or to many local garages and auto parts stores that offer recycling facilities. Always check with your local authority for specific disposal instructions in your area.

Frequently Asked Questions (FAQs)

How often should I change my engine oil and filter?

The frequency depends on your car's manufacturer recommendations, driving conditions, and the type of oil used. Modern cars with synthetic oil might have service intervals of 10,000-15,000 miles or every 1-2 years. Older cars, or those running on mineral oil, typically require changes every 3,000-5,000 miles or every 6 months. If you do a lot of short journeys, stop-and-go driving, or drive in extreme temperatures, more frequent changes are advisable.

Can I mix different brands or types of engine oil?

While it's generally not recommended to mix different types (e.g., mineral with synthetic) or viscosities, most engine oils are compatible to some extent. However, for optimal performance and protection, it's best to stick to one type and brand that meets your car's specifications. Mixing can dilute the additive package and reduce the oil's overall effectiveness.

What happens if I overfill the engine oil?

Overfilling can be as detrimental as underfilling. Too much oil can cause aeration (foaming) when the crankshaft whips the excess oil, leading to reduced lubrication and potential engine damage. It can also increase pressure in the crankcase, potentially blowing out seals and causing leaks. If you overfill, it's best to drain the excess oil until the level is correct.

Do I need to change the oil filter every time I change the oil?

Yes, absolutely. The oil filter traps contaminants that accumulate in the oil over time. Reusing an old filter with new oil would immediately reintroduce those contaminants into your fresh oil, negating much of the benefit of the oil change. Always replace the filter with a new one during every oil change.

What are the signs of a failing oil filter?

A failing or clogged oil filter can lead to reduced oil pressure, which may trigger your dashboard oil pressure warning light. Other signs include a noticeable drop in engine performance, unusual engine noises (due to lack of lubrication), or unusually dirty oil shortly after a change. However, these symptoms can also indicate other serious engine problems, so it's always best to investigate promptly.

Mastering the oil and filter change is a fundamental skill for any car owner. It provides a deeper understanding of your vehicle, saves money, and most importantly, contributes significantly to the longevity and reliability of your engine. By following these steps carefully and prioritising safety, you'll ensure your car continues to run smoothly for miles to come, giving you peace of mind on every journey.

If you want to read more articles similar to Your Guide to a Spot-On DIY Oil & Filter Change, you can visit the Maintenance category.