First my wife is filing for divorce. Second, my psychologist gave me a diagnosis today of why I acted the way I did that caused my wife to want a divorce (Post traumatic stress disorder). My wife and I married in October 2002 and was pregnant with our daughter who is now 5 1/2 years [...]

Vast majority of them are 30 wt. You probably would not have a problem with 40 wt in very warm climates. I would locate a manual or call the engine manufacturer and ask about 10/30 or 10/40. I think craftsman carries briggs and stratton. God Bless