@2davidc8 you’re allowed a certain amount of leeway in checking your oil levels. That’s what the hash marks mean at the top of the dipstick measuring point: “your level should be in this area”. Because obviously, if you’re driving across country and want to stop for fuel and check your oil, you don’t want to sit there for four hours (okay, 20 minutes in New England at this time of year) for the engine to cool to get a “cold” reading.
The fact is that oil, like many materials and fluids, expands a bit as it warms, so your level will change based simply on the temperature of the fluid. In addition, as you operate the vehicle the oil is moved through its cycle to lubricate the various pieces and parts that it has to lubricate, so a recently-run engine is going to have a certain amount of oil – because of its viscosity – still draining into the pan. (In point of fact, the warmer oil is also somewhat less viscous than cold oil, so you’ll want to drain “warm” oil from an engine in order to change it, because that way you’ll be draining the highest quantity of used and contaminated oil.)
I’m not going to tell you to do anything against the advice of the vehicle manufacturer, who will undoubtedly have perfect technical instruction on how to measure your oil level. But as you gain experience you’ll also know that there are many acceptable methods: before operating the vehicle and while it is “cold” will give you one reading, and by using the method you described will give you a slightly different reading. (Try both ways over a period of time to get an idea of the difference that “the same level” may indicate. This is also a good way to become familiar with your car under the hood when “cold” and when “hot” and how to recognize what is normal in both cases. Be careful while under the hood with a hot engine; some parts retain more heat longer than you might expect – and hotter, too! – and can cause significant injury. You should also be aware – and surely your owner’s manual will mention – that certain electrical and mechanical systems in your car may operate unexpectedly, such as electric fans that may continue to operate, or turn on and operate by themselves, in a recently switched-off vehicle.) Definitely read your owner’s manual: RTFM.
Your way of measuring is just as valid as mine, but if you only take one cold reading and one hot reading you may think there’s a problem when all you’re really seeing is the normal variation between “hot” and “cold” of the same – perfectly normal and acceptable – level of lubrication ability.
PS: While you’re looking at your dipstick also look at the color of the oil. Although oil is popularly considered to be black, if you look at new lubricating oil poured into your oil reservoir you’ll see that more often than not it’s a mellow, brownish-to-golden honey color. If your dipstick is showing “black” oil, then it’s probably time for an oil change.