Throughout the game X and Vile can collect Heart Tanks to upgrade their current hit points, here are Vile's Heart Tank locations.
Within the eight main levels of the game, there lies a Heart Tank or "Life Up" waiting to be discovered. Finding these items will increase your health. I shall now list each of their locations.
If you pass over the X-Buster upgrade found in a Dr. Light capsule during the game, you will be rewarded later in the Sigma Fortress by gaining access to Zero's Buster, which is more powerful than the normal X-Buster upgrade. To do this, simply do not enter the Dr. Light capsule containing the X-Buster upgrade, and play the game all the way to the third Sigma level. Upon facing Vile and beating him in a battle, you will speak to Zero and he will give you his buster. This buster shoots a different third level charge shot than Dr. Light's upgrade, which is larger and more powerful.
After you beat the game with Vile and saved a Clear Data for it load up the clear data and when you select your weapons your slots will be infinite.
When you beat the game you will get a new title screen showing X and Vile surrounded by flame.
Successfully complete the game as X.
Note: You must have completed the game to do this. Use the following with Vile.
Throughout Megaman X lies Sub-Tanks that save up extra energy to use it in a battle when you're running a little low, here are Vile's Sub-Tank locations.
Throughout Megaman X there are Sub-Tanks that hold extra energy for a quick boost when you're running low on life, here is where they are hidden.