Driving/Maintenance/Minor service

Many factors go into determining the maintenance period. In the absence of specific guidance from the manufacturer, a perform minor service should be performed no less than once every 10,000 miles or once per year, whichever occurs first, regardless of any and all conditions. With good conventional oils in modern engines, service intervals of 15,000 miles or more are viable.

Oil change
At each minor service interval, an oil change must be performed. Oil lubricates and cleans the engine, and transfers heat to the oil pan and crank case; dirty oil becomes less effective at all of these things, and may fail to flow through smaller channels, starving small moving parts for oil and leading to engine damage.

Cheap motor oils such as gas station and auto parts store brands should be avoided. Higher end brands like Valvoline and Mobil 5000 supply much better quality oil than these; but other common brands such as Prestone and Castrol do provide superior quality motor oils as well. The major difference between $1.50 gas station oil and $4 name-brand oil is the additives in the oil: the viscosity stabilizers and anti-wear additives in Valvoline are selected, tested, balanced, and adjusted to compete with Mobil, Prestone, and Castrol GTX for engine protection and oil life; the viscosity stabilizers and anti-wear additives in cheap motor oil are there to get it an SAE 5W30 rating, and nothing more.

When it comes to conventional and synthetic blends, there's little price difference; this is because synthetic blends can contain 5% synthetic oil and still be marketed as synthetic blends. Full synthetic will outperform synthetic blend in all cases, with a higher price tag; however, full synthetic should not be used in an engine with oil leaks, or on the first 3000 miles of a new engine. An engine that performs well and doesn't leak or burn oil can safely accept full synthetic oil. Rotary engines, such as those in the Mazda RX-8, must use conventional oil.

All manner of heavier oils, lighter oils, and oil additives should be avoided, except perhaps for anti-wear agents in special circumstances; older engines require zinc additives to prevent major wear, and newer oil does not contain this. Beyond this, oil additives serve little purpose except to cover up problems such as worn pistons and valves. Some additives help muffle engine knocking, but the pre-ignition causing it continues to damage the engine. Oil stabilizers such as Lucas can cause the oil to maintain gas bubbles, reducing lubrication and cooling; they can also thicken the oil, reducing flow to small engine parts.

Heavier oils and oil additives that thicken oils both cause reduced oil flow. A heavier oil will help prevent blow-by, improving power output from the engine; however, it will also impede flow through smaller oil channels, starving small moving parts for oil and causing engine damage. Lighter oils will help improve gas mileage by flowing easier; however, heavier oils provide more lubrication, so lighter oils than manufacturer specified will cause increased engine wear. The manufacturer specification is the heaviest oil safe to use in the engine, and should be followed whenever possible.

Finally, the oil filter must be changed at every service. A high-quality oil filter should be used; such filters often use a greater surface area inside, multiple layers of filter material, metal structural parts, and superior bypass mechanisms. Because of this, they are able to provide more fine-particle filtration, better flow, better durability, longer operational life, and more reliable recovery from oil filter failure. Most low-end store brand filters are FRAM; high-end filters like K&N Gold and Mobil 1 tend to cost $10 instead of $5. FRAM makes high-end filters for use by NASCAR, which operate on a completely different design than the commonly rebranded FRAM filters.

Tire rotation and inspection
On most vehicles, tires wear unevenly. Imbalanced suspension systems, asymmetric weight distribution, driving conditions, and two-wheel-drive layouts cause some tires to experience more stress than others. Even a proper all-wheel drive vehicle supplies power to the rear wheels, and uses a fluid coupling to distribute power to the front wheels when the rear wheels slip; this means that all-wheel drive and two-wheel drive vehicles wear the rear wheels faster, while front-wheel drive vehicles wear the front wheels faster.

At each service, the tires should be rotated to even out wear distribution. For directional tires, the rear tires should switch with the front on the same side; for non-directional tires, the set not getting power should swap. So, rear- and all-wheel-drive vehicles would move the front-left tire to the back-right, and the front-right to the back-left; the back-left would move to the front-left, and the back-right to the front-right. Front-wheel drive tires would cross the rear tires instead. This greatly improves tread life, allowing the tires to last much longer than if they just stay at the same positions.

A tire inspection should be performed while rotating the tires. Any excessive tread wear requires replacement of the tires; any uneven tread wear requires repair to the suspension system, possibly something as simple as a front-end alignment. Such a tire inspection can reveal minor but serious problems that a mechanic can correct before the stress on the suspension system or other components creates a much more serious and more expensive to repair problem. Fixing such issues also tends to allow the wheels to turn more freely, improving handling, power, and fuel economy.

The tire pressure should be checked at each service as well. Any mechanic can easily fill tires to the proper pressure, reducing wear and improving handling, traction, and fuel economy. Many mechanics perform a tire inspection and inflation as part of any service involving the wheels or tires, such as a tire rotation.

Brake inspection
When the tires come off the car for rotation, the brakes are exposed. At this point, the brake system can be inspected, cleaned, and bled; at the very minimum, a brake inspection should be performed. Oftentimes brake calipers will become unbalanced, or brake fluid will leak, or brake pads will be worn enough that a visible inspection will reveal the need for repair well before the driver feels any trouble with the brake system. A skilled mechanic can detect all of these problems just by briefly examining the braking mechanism during a tire change or rotation; many mechanics inspect the brakes as part of any service that requires removal of the tires.

Brake parts can also be gently serviced while the wheels are off. This includes cleaning with brake parts cleaner, as well as a more labor intensive bleeding of the brake system to remove any trapped air, if required. Excess trapped air may indicate a brake system leak, a low brake pad needing replacement, a replaced part such as a brake caliper, or old brake fluid requiring a brake system flush. Excess trapped air will decrease braking force, and eventually lead to brake system failure. Brake bleeding usually isn't required unless some other problem exists or was recently corrected by a parts change.

Body and chassis lubrication
The vehicle body requires regular lubrication for all hinges and joints to prevent wear and rusting. This is typically as simple as using a small oil can to inject motor oil into the hinges and latches of the doors, hood, and trunk. The locking mechanisms can also be lubricated through the key hole with the proper lubrication.

In some vehicles, the CV joints and other suspension components need grease injected into the boots occasionally; in others, the boots seal well enough that the same lubricant lasts for the service interval of the joint itself. A mechanic can perform this service in the course of a normal oil change, for additional cost; this greatly improves performance and lifetime of the vehicle. Many vehicles only require this at longer intervals, such as 30,000 miles.

Fluid and belt inspections
All minor inspections should occur during a minor service. This includes the inspection and topping off of all fluid levels including coolant, transmission fluid, brake fluid, clutch fluid, battery water, and wiper fluid; as well as all hoses and belts in the vehicle. A mechanic may notice problems with these systems that the driver had not noticed during minor inspections at fueling, such as dry-rotted hoses or belts.