I don't understand what you mean where is the sump? can you explain

Is it safe to mix two Castrol oils I need 6.5 liters the new one I bought is 5 liters plus I have some left over of the Castrol high milage I used last time
so 5 liters of gold Castrol and 1.5 liter of the high milage Castrol

 

When you add oil in the fill cap on the valve cover, it will drain through the sump.

I am of the belief that it is ok to mix different oils as long as they both meet the specs for the car. I don't know if those do. Not many meet Jag's spec.

 

The "sump" is the lowest point of the oil pan, the portion that dips down and provides the oil a place to collect, where the oil pump can draw the oil from, and re-circulate it through the engine. Below, is a small block chevy oil pan, but it clearly illustrates what a "sump" is......

 

The drain bolt is at the bottom of the sump? or the sump never gets empty? even when you drain the oil? which is why lotues was telling me to add more oil to clear the sump?

 

The drain plug is always at the bottom, but depending on the design of the oil pan, it may not get every last drop out, which is why I said you can pour some extra clean oil through the engine to be extra sure.