In the past 5w30 was the rec. oil for my 2000 F150 4.6 V8. Now, I'm seeing that I'm suppose to be using 5w20.

Why????????????????

 

Fuel efficiency.

It really doesn't matter. I would just use what you've been using.

On hind sight, I use whatever is the cheapest in my '07 Jeep Compass that has over 300k miles on it. Owned it since 7 miles on it brand new. So I know I've used the 0W20, 0W30, 5W20, and 5W30 throughout it's lifetime. It's recommended oil is 5W20. Then again, the 2.4l World Engine is one heck of an engine in terms of durability. The rest of that vehicle? Eh, not so. It's my cash car... get's me back and forth from work to home reliably.

 

5W20 is for eco boost engines, as written on the Castrol oil bottle ; I've tried it but my maintenance garage advice me to change for the 5W30 ... but my F150 is a 4,6 l 1997 model with a rebuild engine....

 

Ford recommends 5W30 for the Ecoboost because of fuel dilution with the direct injection, doesn't matter what the Castrol bottle says. Your 97 originally recommended 5W30, but Ford changed the recommendation to 5W20. You can use either 5W20 or 5W30 in it with no issues.

 

I have switched to 5W30 in my 2002 5.4.