Conventional oil, also known as mineral oil, is the traditional choice for engine lubrication and remains a widely used option for many vehicles around the world. Derived directly from refined crude petroleum, it provides the essential function of reducing friction between moving engine parts, preventing wear, and ensuring smoother operation. Typically available in various SAE viscosity grades such as 5W-30 or 10W-40, conventional oil offers reliable performance under normal driving conditions, making it suitable for older engines, low-mileage vehicles, and daily city commutes. It contains basic additives such as detergents, anti-wear compounds, and rust inhibitors to provide adequate engine protection, though its resistance to oxidation, extreme heat, and cold weather is limited compared to synthetic oils. One of its main advantages is affordability, making it a cost-effective solution for routine oil changes, though it usually requires shorter change intervals of around 3,000–5,000 km or every 3–6 months. While it does not offer the advanced cleaning, fuel efficiency, or extended life benefits of synthetic oils, conventional oil remains a dependable choice for drivers seeking a budget-friendly option with proven effectiveness. However, due to its higher environmental impact, proper disposal and recycling are essential for sustainability.