In a medium saucepan, heat milk, salt, sugar, and butter until butter has melted. Let cool to room temperature.
Place flour in a medium bowl. Make a well in the center, and add oil and eggs. Beat until the batter is too stiff to beat and is smooth, 2 to 3 minutes. Add the milk mixture little by little, beating until smooth. Strain the batter through a fine sieve, and then whisk in beer. Chill overnight.
Heat a crepe pan over medium-high heat until a drop of water sizzles in the pan. (The first crepe may stick a little if your pan is not heated to the proper temperature.) Rub the pan with a little butter, wiping out the excess with a paper towel. Ladle a thin layer of the batter (about 2 tablespoons) into the center of the pan, tilting and rotating the pan to cover the bottom as thinly and evenly as possible. Lightly brown the first side for 1 to 2 minutes. Gently flip the crepe over, and brown the other side for about a minute. Turn out onto plastic wrap. The crepes may be covered and kept at room temperature for a few hours or refrigerated for up to two days. To reheat crepes, place in a covered baking dish, and transfer to an oven heated to 400 degrees until heated through.
To serve, spread warm crepes with jam or butter. Drizzle lemon juice over the butter, and sprinkle with sugar. Fold into quarters, and serve immediately.