you should check your owners manual, but if you don't have one this will get you started. most engines of that size take about 5 qts. with a filter change, so after you have put in about 3 qts check the level with the dipstick--just to make sure it is still low. then add another qt. and check again. at this point you should have put in 4 qts and the level on the dipstick should show that you are 1 qt low--that would be to the lower mark on the dipstick. from there you just need to top it off until you get the right reading on the dipstick, but it'll likely need that full 5th qt. just make sure you do all the above on level ground to get the proper readings, and i'd double check the level again after driving the truck around for a while. good luck.
6qts. with filter
4 quarts. 5 if you have the ecotec engine.
What size engine do you have ?
The engine holds 5.
According to the 2002 Ford Windstar Owner Guide : With engine oil filter change ( 5.0 quarts )
All the 2008 Chevrolet Trailblazers (with V8 engines) hold 6 quarts of oil, but the 4.8L V6 engine can hold 7 quarts.
It takes 6 quarts of oil.
( 6 quarts ) with engine oil filter change
( 5 quarts ) with engine oil filter change
The Haynes manual specs 4 quarts (with a filter change) FriPilot
According to the 2004 Ford Taurus Owner Guide : With engine oil filter change : The 3.0 liter " Vulcan " V6 engine takes ( 4.5 quarts ) The 3.0 liter " Duratec " V6 engine takes ( 6.0 quarts )
7 Quarts