"Buy some oil stock and pay cash for the house"
Agree with the first... but the second??? NO.
Not at these interest rates. An example top....
Say real estate values go up 2% this year. You have a 300k home. Value of home goes to 306k. If you have home paid off you make the 2% on your equity. Now say you had 20% equity in the home (60k).... now if the home value goes up 2%... you still make 6k, but on 60k equity so you earn 10%.
Take the remaining 240k and invest it in securities making 9% income. That produces $21,600 in income. If your credit is good, you can still get a 30 year fixed for about 6%. That means you clear 3%, not counting the ability to deduct the interest from your taxes and more than likely giving you the opportunity to itemize deductions rather than simply taking the standard.