The Brison manual states that a good synthetic oil, mixed at a ratio of 80-1, should be used on all of their engines from day one. One of my 3.2's has five years on it and it runs just fine. The others have between 1 and 2 years and they also run fine at that oil mix. My 6.4 is run at exactly the same ratio with no worries at all.

It's difficult to go wrong when you go with the manufacturers recommendations.

Pat