So, my girlfriends 2001 Corolla burnt through all of its oil in 2500 miles,(I put in pennzoil 5-30 with a fram filter in at 122k she is at 124.5k now) she then drove 50 miles without knowing and thinking the oil light was just a door ajar light or something. Anyways! The engine must be ruined right? I put a few quarts of shit oil in it, and next week I'll be putting in a heavier weight oil. The car calls for 5w-30 but I was told I should put 20w-50 to stop it from burning off. Any tips would be appreciated as to if its the right oil to use and any other tidbits.

Edit:

Gonna have her put a piece of cardboard underneath tonight to check for leaks, then when she comes back to my neck of the woods I'll put it on my lift. Until then, I taught her how to check the oil level with the dipstick and told her not to drive around for fun.