If RVS isn’t an oil additive product, why is the oil capacity important information in choosing the correct product?

The oil capacity is comparatively easy to find out for your vehicle, and normally it defines sufficiently well how much area there is to treat in the mechanism. Thus it is important to choose the right RVS product for your exact application and therefore guaranteeing there is enough of it to perform the restorative and protective functions as designed.
In industrial applications with external oil tanks and relatively low flow speed, other criteria are used for calculating the appropriate RVS Technology™ product amount.