best motor oil to use in a 351 w engine in my 87 f 250

 

The definition of 'best' depends on the conditions your engine will be operating in.

If you live somewhere with zero degree winter weather a 5w30 oil will aid cold starts and give more prompt lubrication.

If you live in a milder climate, 10w30 is a good all season oil.

Scott

 

or if the engine has a lot of miles on it i go by oil pressure. if its low ilding hot, i go with a thicker oil. i run 20w50 in my 83 in winter and 40w in summer because my bearings are shot.