oil_6month <- forecast(oil_monthly, h = 6)

# Let's have a quick look at the 6-month forecast and the 80%/95% confidence levels. 
oil_6month
##     Point Forecast    Lo 80    Hi 80    Lo 95    Hi 95
## 135       53.99987 47.53908 60.46067 44.11894 63.88081
## 136       53.99987 44.84351 63.15624 39.99642 68.00333
## 137       53.99987 42.76141 65.23834 36.81212 71.18763
## 138       53.99987 40.99460 67.00515 34.11002 73.88973
## 139       53.99987 39.42782 68.57193 31.71385 76.28590
## 140       53.99987 38.00211 69.99764 29.53340 78.46635