plaid red Knights Sportswear 4XLT Plus Size shirt- w small stain

Plaid red size 4XLT men's shirt. Knights Sportswear brand, 65 percent cotton and 35 percent polyester. Has one pocket, buttons on collar, and one extra button. My husband was a car guy, and there's a small stain on bottom front of shirt that I assume is automotive. It might be able to be gotten out. But even if not, if you're a guy who wears his shirts tucked in, no one but you will know it's there.