Noob question guys.

Wala ako alam sa sasakyan and this is my first time to have one.

Nung nilabas namin sa casa yung sasakyan nag pa gas kami sa caltex silver unleaded... Advisable ba or it's must na sa caltex ulit ako mag pa gas?

If hindi naman must, Do I need to empty the fuel first bago ako mag pa gas sa ibang gas station like petron or shell?

Thanks!