Ok,,we in here have no clue as to what oil u have used, what mechanical background ur engine has, etc. But in MHO, u should use 10w30 at least or 10w40 oil. U will not blow up anything, and its a good way to find out if the 5w20 is just to thin in ur part of the world or for that 3.8. I have had one car with a 3.8 and I used 10w30 or 40 and no oil usage with either one. Currently I run 5w40 in my van Rotella t6, but that's me and it works great. But try the 10w30 or 40 . If u have already done this in the past and u were using oil, then drive the van down to the nickel shredder , drop it in and push the (new van button) and there u go,,out pops a new ride. PS, just kidding on the shredder thing.lol