He will be "OK" with any higher SAE grade as long as the winter rating is appropriate for his expected starting conditions. That's related to his location which continues to be undisclosed.Back in the day I used M1 15-50 in my 1992 Ford explorer and then my S-10 2.8L from dai one and never had a problem here in S Fla. Now I use what the Mfg says, I do have Jeep Grand Cherokee and as soon as it's out of warranty I will switch from 0-20 to 5-30. I think you would be OK with a 5-30 but no heavier than that. If you wante to save some $ use the Kirkland mentioned or Supertech from Wally world.