I was just reading through the owners manual and it says they "strongly recommend" 0W – 20 oil and do not recommend the use of other viscosities except for short-term use when 0W – 20 isn't available. Thicker oils will prolong warm-up time and reduce fuel economy. In the long run it puts extra pressure on the seals and gaskets as well. Not really a good idea to do. These modern engines have very tight tolerances .