Revving your engine, especially when it's cold, is generally not advisable. While it might feel like a way to warm up your car faster or show the power of your engine, it can actually be harmful. Cold revving can cause abrupt temperature changes that stress engine components, leading to premature wear. Additionally, modern engines are designed to warm up efficiently at idle, making revving unnecessary for this purpose. However, occasional revving at operating temperature, in a controlled manner, might be beneficial for clearing out carbon deposits and ensuring the engine and exhaust systems are functioning properly. It's essential, though, to ensure the engine is fully warmed up before doing so, to avoid damage. Always follow your vehicle manufacturer's recommendations for engine care and maintenance for the best performance and longevity.

The term "bulletproof engine" is colloquially used to describe an engine that is extremely reliable, durable, and capable of withstanding heavy use without significant problems. It doesn't imply literal resistance to bullets but signifies that the engine design, materials, and build quality are of such a high standard that failures are rare. Often, these engines have proven track records in various conditions, being able to endure extreme temperatures, long distances, and rigorous usage. Manufacturers achieve this through precision engineering, quality control, and sometimes, over-engineering parts to exceed normal operational stress. Bulletproof engines typically require regular maintenance but are less likely to need major repairs, making them desirable for vehicles in demanding roles, like commercial trucks, emergency services vehicles, or off-road vehicles. When opting for a vehicle, an engine with a reputation for being bulletproof is a significant factor for those prioritizing reliability and longevity over other attributes.

Here are the general steps you'll need to take in order to replace the engine air filter of a 2017 Nissan Altima: Materials You Will Need: 1. New air filter (purchase the correct one for your vehicle model) 2. Screwdriver (depending on car model) Make sure you're parked on a level surface and have put your car in park and pulled the parking brake before starting this task. Steps: 1. Open the hood: Find the hood release inside your car (usually located under the steering column) and pull it firmly. Go to the front of the vehicle and feel under the hood for another latch to lift the hood up completely. 2. Locate the air filter box: The air filter is usually located at the top of the engine in a black plastic box. It should have a thick, ribbed tube going towards the engine. 3. Remove the air filter box cover: The cover is typically held in place by four to six metal clips. You just need to unlatch these and gently lift up the cover. In some cases, you may need to unfasten some screws. 4. Take out the old filter: Lift the old air filter out of the box. Be careful not to knock any debris into the bottom of the box. 5. Clean the air filter box: Now that the old filter is out, it's a good idea to clean out the box in which it sits before putting in the new filter. Simply wipe it out with a damp cloth. 6. Insert the new air filter: Place the new air filter in the box. Make sure it's sitting flat all the way around. 7. Reinstall the box cover: Replace the cover and hook the clips back into place. If your cover was held by screws, screw them back in. Close the hood securely when you’re done. Remember safety first. If you don’t feel comfortable doing this task, you should seek help from a professional mechanic. Make sure to refer to the owner’s manual for more precise instructions based on your specific model.