3.8 V6 Starting problems

[2002 F-150 FX4]

I'm trying to help out my buddy with his 3.8 V6. When its below 20 the engine has a hard time turning over. Thought it was the battery replaced it still having the same problem. Is it the alternator? or is it somthing else? It doesn't sound like its the starter.
If any one has an Idea what it might be?

[BrianA]

You might want to do a voltage check on the battery just to be sure. It does sound like a low battery condition.
The alternator doesn't come into play when cranking. It just keeps the battery charged while driving. So, if the alternator is not charging the battery properly, then even the new battery might be weak.

Maybe try throwing a battery charger on it for a 1/2 hour before starting on a cold morning to see if that helps.

Also, what oil is he using? Heavier weight oils will get pretty thick on cold mornings and can lead to slow engine turn-over.

[tyc11388]

i agreeyou need to use the 5w20 recommended by ford