Why Does Fuel Consumption Increase After Maintenance?

[LeEmery]

The reasons for increased fuel consumption after maintenance include higher oil viscosity and replacement of brake pads. Detailed explanations are as follows: Higher Oil Viscosity: Excluding the use of different oil, even with the same oil, newly replaced oil will have higher viscosity compared to oil that has been used for 10,000 kilometers. This naturally creates greater resistance, leading to higher fuel consumption under the same road conditions and driving habits. This situation usually diminishes after a few hundred kilometers of driving. Replacement of Brake Pads: After installing new brake pads, the friction gap is relatively smaller, resulting in greater resistance during braking, which can slightly increase fuel consumption. This issue resolves after the brake pads' break-in period. Slightly Overfilled Oil: Excessive oil increases the energy required for the crankshaft to rotate, thereby adding to the engine's load and naturally increasing fuel consumption.

[MartinLynn]

I just had my car serviced and suddenly noticed the fuel consumption skyrocketing - been there myself. The most likely culprits are either overfilled engine oil or using the wrong viscosity grade, like putting in 10W-40 when the manufacturer recommends 5W-30. Thick oil like honey will definitely make the engine work harder. Next, check if the air filter is properly installed - once an apprentice mechanic misaligned my airbox clips causing air leaks that messed with combustion efficiency. Don't forget to recheck tire pressure too; if it's below 2.2 bar after maintenance, those tires dragging against the road will guzzle fuel. Also, if the ECU wasn't reset after throttle body cleaning, it'll keep calculating fuel injection based on dirty conditions - total waste. My advice? First check the dipstick levels, then monitor over two full tanks of gas to rule out temporary ECU reset anomalies.

[McMary]

Last month after the maintenance, the fuel gauge dropped unusually fast. I figured out a few key points: the viscosity of the engine oil is the most critical factor. If you switch from full synthetic to mineral oil or use a higher grade, the piston movement resistance increases during cold starts, immediately raising fuel consumption by 10%. The air filter is also prone to issues; if the new paper filter element gets wet with oil or water, the air intake becomes worse than with an old filter. I also encountered a situation where a mechanic tightened the spark plugs too much, causing poor ignition. With one out of four cylinders not working properly, it's like wasting 25% of the fuel. It's best to keep an eye on the oil specifications during maintenance, reset the car's computer immediately after picking up the car, and calculate the real fuel consumption after running through a full tank of gas.

[Aurora]

Three common pitfalls after maintenance that cause a sudden surge in fuel consumption: First, overfilling engine oil—exceeding the upper limit by 1cm will inevitably increase fuel usage. Second, installing a substandard oil filter with a faulty internal check valve, which slows down oil pressure buildup during cold starts. Third, skipping wheel alignment after tire rotation, leading to uneven tire wear and increased rolling resistance. Also, over-tightened brake pads post-maintenance can heighten friction. Immediate checks recommended: inspect the oil dipstick level, test brake disc rebound by hand, and listen for abnormal tire noise on highways—all simple DIY diagnostics.