I want to use the oil additive Bell Hammer Seven. Is it compatible with my oil? I use WAKO'S Pro Stage S 0W-20. My hybrid car is over 10 years old and worn overall, but the engine is running well.

Bellhammer Seven is compatible with a wide range of engine oils and can basically be used with any oil.
It can also be used with the WAKO'S PROSTAGE S 0W-20 that you are currently using without any problems.

However, please consider the following points.
Viscosity change: Adding Bellhammer Seven may slightly change the viscosity characteristics of the oil, but even low viscosity oils such as 0W-20 will function without problems if the right amount is used.
Engine condition: If the engine is running well, further smooth rotation and quietness improvement can be expected due to the lubrication and friction reduction effects of Bellhammer Seven.
Recommended usage amount: Ideally, an appropriate amount (approximately 5% to 10%) should be added to the total amount of engine oil. Please observe the proper amount as excessive addition may change the original oil balance.
It can be used for hybrid vehicles without any problem, so please give it a try.