My '85 takes about five minutes, depending on how hard you are driving. I drive the same route to work every day. I see my oil and water temps go from low to 150 degrees at almost the same point in my trip. My water hits 180 degrees or so depending on if I get caught at a light, then my oil hits 150 degrees about five minutes later. Also, I have an oil cooler, which makes a difference (heats up oil faster).