94 ranger oil question

I 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?

My manafacturer suggests using 5W-30 during the cold seasons and 10W-30 during the how summer seasons. But of course engine wear can cause engine to loose oil if its a lighter weight.

Evil's advice is good and you should follow it.
The manufacturer specifies oil for a variety of reasons. One reason is to better meet government regulations for emissions and fuel economy

Engines that use 5W-20 get slightly better gas mileage because the oil is easier to pump, especially when cold. Therefore emissions, especially cold start emissions are lower and gas mileage is slightly better. You likely won't notice a difference, but even a tiny difference in each car helps the manufacturer a lot, since they make more than a million vehicles each year.