Hello, Please remember no question is a stupid question! I purchased a new water pump (112-200-14-01-88) from MB dealer and in the box it has two gaskets. One I would define as an 'o-ring' and the other one a 'gasket'.

After removing the old pump, I noticed that only the 'o-ring' was used before, so no gasket was used.

Should I use both when replacing water pump or simply the gasket?

Thanks
Nikki