Cheap alternative to pricey flat tappet oil in street cars...

I have a 92 suburban with a flat hyd cam ,with everything stock and 250000 miles and the only thing I changed was the timing gears ,I've only used the cheapest oils I could find but did change it every 3000 miles. 10w30. I drive this truck everyday ,unless your using high spring pressures on the valves, regular oil is fine ,most of the fuel Inj engines have smaller cams ,less pressures on the cam lobes if stock.