Can one substute SAE 30 for 5W-30 oil?

SAE 30 and 5W-30 oil serve different purposes due to their viscosity ratings. SAE 30 is a single-grade oil suitable for warmer temperatures, while 5W-30 is a multi-grade oil designed for a wider temperature range, providing better performance in colder conditions. Substituting SAE 30 for 5W-30 may lead to inadequate lubrication during cold starts and reduced engine protection. It’s best to use the oil recommended by the manufacturer for optimal engine performance.