You mean the Stroh "fire brewed" Lager? I used to buy those too, and really enjoyed them before smaller scale brews and craft beer became the rage.
It's a typical adjunct based American Light Lager, like so many that are abundantly available (BMC: Bud, Miller, Coors).
Yet (!), one of the most difficult styles to brew for homebrewers, due to the plethora of process parameters we cannot tightly control as they do in macro breweries. Not impossible, but it takes a lot of practice and dedication, as any flaw or deviation in the process will show up, as there is nothing to hide them behind. Basically on the very other end of the spectrum when compared to say, a homebrewed Stout.
Chances are, I doubt you will be able to please him on that front, especially in the short run.
But there are alternatives. You haven't disclosed your location (you can put it in your user profile), there are (smaller) breweries that produce excellent lager beer, most that, IMO, surpasses most macro beer (BMC). For example, Yuengling, who I'm very familiar with. I used to live 30 miles north of their brewery in Pottsville PA, and they have been my go to "easy drinking" beer for a long time, and I still enjoy them from time to time, especially their Black & Tan.
See if any lager beer from smaller breweries is available in your area's beer shops or distributors and let your granddad be the judge. Many craft breweries also brew excellent lagers now, even American Light Lagers, that flavorwise beat BMC for those who appreciate that kind of brew. No, they won't be the same as Stroh's, but possibly a viable alternative.