What does it feel like to switch from 40 to 30 engine oil?

[TaliaRose]

Switching back from 40 to 30 engine oil is completely fine, but the prerequisite is to purchase genuine oil from a reputable brand. Here are the specific details: 1. Vehicle model: If it's a low-end model that's seven or eight years old, it's still recommended to continue using 40 oil. After all, the engine wear is not in an upward phase, and the gap between the piston, piston rings, and cylinder walls has increased, requiring higher viscosity oil for protection. It is advisable to continue using 40 oil to achieve the effect of protecting the engine. 2. Engine: If the vehicle has a turbocharged (T) engine, due to its more precise construction and higher requirements for oil, it is recommended to use fully synthetic oil. For naturally aspirated engines, semi-synthetic oil can also meet the usage requirements. Different oils have different replacement cycles: semi-synthetic oil should be replaced every 7,500 kilometers or about 8 months, while fully synthetic oil, if used carefully, can be replaced every 10,000 kilometers or once a year.