Zinc oil additives

73smallblock said

I was talking to an oil rep one day and he was totally against using zinc additives that was not formulated in the oil. He basically said that if wasn't in the oil, then it probably wouldn't mix in the oil and may just lay in the bottom of the pan. He wasn't selling any special oil to me just a conversation about zinc in oils vs additives.

Click to expand...

I find it impossible to believe that the additives would just sit in the bottom of the pan.
The sump is supposed to sit on the bottom of the pan and suck out all of the oil mixture and send it through the oil galleries of the engine and then it drains back to the pan and is always recycled and the additives are in suspension.
Now a different argument to make would be that the detergents wash the Zinc additives off the cam almost right away, so they have little to no affect in preserving the cam and lifters, which is more believable to me...