Mazda 3 Engine Problems
Mazda 3 2006: Cam belt or chain?
It has a chain, so there’s no regular maintenance required. The only reason you might replace the chain is if it were to wear.
Mazda 3 2007: Why is the temperate dropping suddenly?
The engine is most likely overheating, even though the gauge is at zero. Check the coolant level, and for leaks from the radiator or hoses. It could also be a blown head gasket. The bottom line is it needs investigation by a mechanic.
Is a Mazda 3 fuel efficient?
Yes! No! Quite possibly! The largest factor in achieving good fuel efficiency is the nut behind the wheel (the driver). If you drive with efficiency in mind you will find Mazda's sales-dominating compact car will be able to travel hundreds of kilometres between refills, averaging approximately 5.7L per-100km for the 2.0-litre engines and approximately 6.5L per-100km for the 2.5-litre engines.
How to change a Mazda 3's oil?
Drive the car gently for 10 minutes to get the oil warm. Park the car on level ground, lift the bonnet and loosen the oil filler cap on the engine, and slide a tray or pan with at least 5-litres of capacity under the car. There is a flap held on by a couple of plastic screws protecting the drain plug and oil filter. You may not be able to reach the drain plug on the sump underneath the car without lifting the vehicle. If this is the case remember to use multiple chassis stands to securely hold the car in the air, and to ensure the car is as level as possible (so you might need to jack up the rear of the car to keep it flat). After 10 minutes the oil should have stopped dripping from the sump plug so put it back it and snug it tight - don't over-tighten it as you could strip the thread in the sump which would require removing the engine to fix! Remove the oil filter, allowing it to drain, and ensuring the rubber seal isn't stuck on the metal mating surface. Once drained wipe a smear of fresh oil on the new oil filter's rubber O-ring, fitting it a quarter-turn past snug. Check on your owner's manual for how much oil is required for your particular engine, and what grade of oil you should use.
Mazda 3 2016: Pinging sound
Has it just started making the noise, or has it been doing it since new? Try running it on higher octane fuel and see if the noise goes away.
Mazda 3: High idle speed
It’s not unusual for a car to do that on a cold start. That’s the way it has been calibrated and it won’t affect the life of the engine.
Hyundai i30: Would a diesel be suitable for Uber use?
Diesels deliver their efficiency benefits best when on the open road, but it would still be more convenient for Uber use because they'd need to be refuelled less often than the petrol. The only thing I'd be concerned about re inner-city use would be the diesel particulate filter. If you only drive around the city, this probably wouldn't give the DPF the chance to cycle itself every now and again, which can lead to very costly repairs. If you do head out onto the motorway occasionally, this wouldn't be an issue. The new i30 is an excellent small hatch though, and I wouldn't hesitate recommending it.
Mazda 3 2004: Fuel pump failure
Fuel pumps are a relatively common failure across many makes and models, but two in a year does seem too much. They shouldn't leak when they fail as they're in the fuel tank. Regularly running low on fuel can cause the pump to overheat and fail, it can also stir up any sediment that's on the bottom of the tank and could cause a blockage. You can try approaching Mazda, but I doubt you will have any success, as your car is 12 years old.