duralube/oil additives

i wanted some input on what yins guys thought about oil additives. i talked with a guy that owns and drives and icecream truck, and he swears by duralube. he said after using duralube his temperature gauge didnt go up as high during those tough summer months. and delivering icecream in an older vehicle would be kinda hard on her. so if any of yins guys have used duralube or any other additive and think its a good choice i would love to hear from ya. 1993 cvpi 101,000 miles.