Can Fully Synthetic Oil and Semi-Synthetic Oil Be Mixed?
2 Answers
Fully synthetic oil and semi-synthetic oil cannot be mixed. The method for changing the oil is as follows: 1. Lift the car, remove the protective plate, and place a container of about 10 liters under the oil drain screw; 2. Unscrew the oil drain screw, use an air gun to blow for two minutes at the oil filler port, then tighten the oil drain screw and wipe it with a tissue to check for oil leaks; 3. Reinstall the protective plate and lower the car, then use a funnel to add oil through the filler port. The functions of engine oil include lubrication, auxiliary cooling, cleaning, sealing to prevent leaks, rust and corrosion prevention, shock absorption, and anti-wear. Engine oils are categorized into mineral oil, semi-synthetic oil, and fully synthetic oil.
As a car enthusiast, I often tinker with my car, and engine oil is a top priority. Can full synthetic and semi-synthetic oils be mixed? I once tried adding half semi-synthetic to full synthetic in an emergency, and the engine ran fine temporarily, but it's not recommended long-term. Different oil formulations vary, and mixing them can cause viscosity or detergent conflicts, leading to sludge formation or reduced lubrication. New cars are especially sensitive, potentially increasing wear or even causing malfunctions. I recommend sticking to the same oil type during each change—if the manual recommends full synthetic, use it entirely. Semi-synthetic is cheaper, but don’t cut corners where it matters. Also, pay attention to oil change intervals: full synthetic typically lasts 8,000–10,000 km, and mixing can disrupt this cycle. Remember to check oil levels regularly, and if low, top up with the same oil first. Safety comes first—don’t save small money only to spend big on repairs!
