Is it safe to switch from fully synthetic to mineal oil?

[sx460]

I've used fully synthetic for basically the life of my 3.4 (120,000 miles). is it safe to switch to a mineral based oil? Reason I ask: my car looses about a quart of oil (maybe more) every 3,000 miles. There are higher mileage oils out there that sound like they may help with a possible oil leak that I have (occasionally I can smell burning oil).

 

Is it safe to switch over to a higher mileage oil (like Valvoline's or Quaker State's higher mileage oil) after running synthetic for this long?

[SuperBuick]

Leaking oil has nothing to do with synthetic, it has to do with a leak. Kepp the synthetic in and fix the leak. Its most likely your distributor shaft O-Ring.

 

-T