[butterfingers]

recently bought a 94 ranger with a 3.0 V6 engine. The place where I cought it form changed the oil before they sold it and put in whats it calls for wich is 5w-20 i think. My mother had a Ford Taurus with the same motor and when we got it it of course had the same oil in it. However after 1500 miles it burned a quart of the light oil so on the next oil change we put in 10w-30 and it never burned a drop since then for the nest 130,000 miles. My ranger seems to be doing the same thing. The oil is gone down from when I bought it after 1500 miles. should I put the 10w-30 in it? Why would a vehicle use the oil it is manufactured and recommended to use?