What does the 'W' in motor oil stand for?
2 Answers
In motor oil, 'W' stands for Winter. The functions of motor oil are: 1. Lubrication and friction reduction; 2. Assisting in cooling and temperature reduction; 3. Sealing and leak prevention; 4. Rust and corrosion protection; 5. Shock absorption and cushioning. Classification of motor oil: 1. Conventional mineral oil; 2. Semi-synthetic oil; 3. Full synthetic oil. The method for changing motor oil is: 1. Lift the vehicle, remove the undercarriage shield, and place a container of about 10 liters under the oil drain plug; 2. Unscrew the oil drain plug, use an air gun to blow into the oil filler opening for two minutes, then tighten the oil drain plug after draining and wipe it with a tissue to check for leaks; 3. Reinstall the undercarriage shield and lower the vehicle, then use a funnel to add oil through the filler opening.
The 'W' in motor oil actually stands for Winter, indicating how well the oil performs in cold weather. Last winter when I drove my old car up north, I noticed it had trouble starting. It wasn't until I asked the mechanic during an oil change that I understood: The lower the number before the W (like 0W or 5W), the better the oil flows at low temperatures, making engine starts smoother. Higher numbers like 10W or even 15W mean poorer cold-weather flow, making them unsuitable for frigid regions. This directly impacts engine protection by preventing cold-start wear. The numbers after (like 30, 40) represent high-temperature viscosity, controlling oil film thickness to prevent overheating damage. Choosing oil depends on local climate - 0W-30 works great in the north, while 5W-40 suffices in the south. I also recommend regular oil level checks: Pull the dipstick after parking for 30 minutes to ensure mid-range levels. Timely oil changes prevent degradation and extend engine life.
