Western and Oil - need the movie title

Hi everyone!

I remember seeing a film in the 1970s (the film is older than that I guess, maybe from 1960s or even earlier, 1950?). I don't know the title of the film and do not know the artists playing in it. But I remember a bit of the story. Don't know if it was pure Western film either.

There was an oil tower, and three people who owned the oil tower, they were attacked by bandits at the end of the movie. One of the owners of the oil tower climed up the tower with an iron plate/shield attached to his back, to protect him from the bullets. One of the bullets obviously hit him an he fell. The bandits then attacked. If I remember it correctly, grenades were used to stop them. The owners of the oil tower were three persons, one girl and two guys. One of them were either wounded or killed during this action. I figure that the female actress was quite famious, although I don't remember who she was. If I remember it right, the oil started coming during this scene, so some of the people were sprayed black.

I guess the film was made in the U.S.

Can anyone give me a clue to what the title possibly could be?

Clue words: oil tower, iron plate/shield, bandits attacking, grenades used, one killed or wounded, fountain of oil, two guys and one girl.

Thank you for your help.

Western1960