I have an '86 245 and an '86 SAAB 900 T, both of which I have stuck with Valvoline 10w40 with a 3K mile change interval for te last 20 years! I personally cannot justify any benefit to switching to synethic. However, these have become "secondary" or "thirdary"(?) cars in our household and see less than 1000 miles per year. It really makes you question than old "3,0000 mile or 3 months" oil change regimen of my youth. Ifm you drive a lo, maybe it might make more sense. Our more mordern cars I have switched to synthetic, My wife drives A LOT for work/kids and there is no way I could keep up, so I use the 15k exended service synthetic and change it every 7k. MY Car came that way, as part of the manufacurer's specification, cheapskate "included service" (we'll only have to chage your oil twice during the coverage period).. Not that I bought it while it still had any kind of service coverage, I just stuck with the recommended oil. It's supposed to be changed every 15K, I change every 7K.