I like the Baja too but I would sell it for a Forester. For some reason, Baja's sell for waaaay more than they should be worth, for a 12-year-old chick-up truck.
NA Subaru EJ25s are fine on dino or synthetic, and do not have the 3750 or 6k recommendation. Some do consume less oil on syn, so your choice there. If you are looking for ultimate inexpensiveness and live near a Rural King (or partner), pick up the Harvest King full synthetic (Dexos1 approved) 5W-30, a Fram XG3593A, and change the oil every 5k and the filter every 10k. These engines with decent oil and maintenance will make 300k easy with timing belt changes on time. My 01 Forester is at 220k and will still get 27.5mpg over a full tank, and uses maybe 1/2 cup over a 5k interval. Other than the long-ago-resolved HG issue on 1998-2003 EJ25s, the NA versions are anvils.
Subaru Coolant Conditioner is the official name of the additive, it is a rebranded Holt's Radweld.