The question you ask is too involved for a proper answer. You need to go to a car parts store, and get a repair manual for your car. They cost about $16.00
moreBEFORE YOU START: Get a roll of masking tape and a marking pen, label every wire, hose, connection ETC. before you take it off. ALSO get a digital camera, and take a picture of EVERY piece before you remove it - - set your camera so that the pics are available in numerical order. You can get a digital card for most cameras that can allow you to take mucho pics - - you don't need to waste space on "best quality" pics, just to remind yourself what went where. Get lots of egg cartons to keep nuts,bolts ETC. and keep them in sequence and label them. NEVER TRUST YOUR MEMORY, NOR THROW ALL INTO ONE CAN !! And, not to insult, but if you were serious in asking this question, you don't know enough to do this yourself. Find someone with much more experience than you apparently have to work with you, please... ~8^)Take your 2002 Ford Ranger to the garage to get the engine checked.
I would need to know what size engine you have and what year of Ford Ranger in order to answer your question
a 1993 ford ranger will hold 5 qts of oil. From the Chilton Ford Ranger guide: A 1993 Ranger with a 3.0 liter engine take 4.5 quarts of oil. The other engine sizes all take 5.0. My 3.0 Ranger takes 5 quarts, Chilton is probably not taking into account of the oil filter.
If service was performed on a 1986 Ford Ranger 2.9L and the code is still showing up, the computer should be reset. Disconnect the positive cable on the battery for a few seconds. This should take care of the problem.
5W-30
According to the 2008 Ford Ranger Owner Guide : For the 3.0 litre V6 engine : With engine oil filter change : ( 4.5 U.S. quarts of 5W-20 engine oil )
According to the 2002 Ford Ranger Owner Guide : For the 2.3 liter four cylinder engine and the 3.0 liter V6 engine ( 5W-20 ) For the 4.0 liter V6 engine ( 5W-30 )
For the 2.3 liter and 3.0 liter engines ( 5W-20 ) For the 4.0 liter SOHC , V6 engine ( 5W-30 ) According to the 2005 Ford Ranger Owner Guide
With engine oil filter change ( 5 quarts of engine oil )
According to the 1997 Ford Ranger Owner Guide : With engine oil filter change : The 2.3 litre four cylinder engine takes ( 5.0 U.S. quarts of 5W-30 )
The 2008 Ford Ranger owners manual shows ( 5 quarts ) of engine oil ( 5 W - 30 ) WITH FILTER CHANGE
According to the 1999 Ford Ranger Owner Guide : With engine oil filter change : The 2.5 liter four cylinder engine and the 3.0 liter V6 engine take ( 4.5 U.S. quarts ) The 4.0 liter V6 engine takes ( 5.0 U.S. quarts )