Difference between 5W30 and 0W20 for Cavalier?

[AmyLee]

0W20 and 5W30 engine oils differ in that the former has lower viscosity than the latter, both in low and high temperature conditions. Numerically, the former is purely a winter-grade oil, while the latter is a commonly used winter oil in northern regions. The former is a less common oil type, while the latter is more prevalent. Below are relevant explanations about engine oils: 1. The "W" stands for winter, and the smaller the number before it, the better the oil's low-temperature fluidity, indicating a lower usable environmental temperature and better engine protection during cold starts. The number after "W" indicates the oil's high-temperature resistance; the larger the number, the better the oil's protective performance at high temperatures. Therefore, 0W-20 is more suitable for lower temperature regions compared to 5W-30. 2. 40-grade oil can be used in any engine without causing damage, regardless of the engine's operating conditions. 0W-20 can only be used in engines specifically designed for this grade of oil. For some engines, using 20-grade oil may cause damage or even failure. The difference between mineral and synthetic oils is not in durability but in their ability to protect the engine under high or extreme operating conditions.