No always. Newer cars (especially GM) recommend changing oil once a year if indicator doesn't suggest shorter period. I would feel confident using synthetic for up to 1 year if mileage is low. 6 months and 1.5k miles is way too low for syn.
It depends on the length of the trips that are taken and the temperature. 12 miles each way twice a week, let it go longer. 4 miles each way 6 times a week, especially in cooler weather, change it at 6 mo.
I have two vehicles that I change it once a year. One gets about 12,000 miles the other less then 3000. On the low mileage one though I try to drive it at least 10 miles every time I start it. The UOA has been fine on both vehicles, been doing this for several years. A cold winter climate would have a bearing though, cold starts of less then 10 miles would be a consideration for a 6 month interval. Best bet, at 6 months do a UOA to see what it looks like for fuel dilution etc. Worht the price at least once, probably after a winter run.