I have a brand new 2003 Ranger 4x4 5,000 miles With the 4.0L SOHC made in Germany. I was looking through the owners manual the other day and noticed that the reccomended oil is 5w-30w. I also noticed that on the oil fill spout, The cap also said 5w-30w.
My Concern is, The Dealer is Putting in 5w-20w.
Should I Be Worried? I have had the truck since it had 12 miles on it, this will be the third oil change when it hits 6,000 miles. The motor runs Great, should I ask for 5w-30w? Is this a valid Question?

 

I think it's a valid question...as far as I know, Ford does not recommend 5W-20 in its 4.0L engines, at least up to and including '02.

That being said, I wouldn't sweat it...Motorcraft 5W-20 is a fine oil. Read here: Fords spec WSS-m2c153-H / 5w-20 oil / what it means .

 

Under NO circumstances do you ever put 5w-20 in a 4.0. Ford had major reliability problems using it in that engine. It is a very high stressed engine. It makes about .88 horsepower per cubic inch. Do not let them do it again. Always use 5w-30 oil and I would suggest one with extra barrier lubes like moly and boron. Most SL rated dino oils have these lubes but examples are Chevron Supreme, Pennzoil, Valvoline, Havoline, and Castrol GTX. You may even consider a synthetic or a boutique oil in your particular engine. Redline or Amzoil performs quite good in this engine. Whatever you use, make sure it is 5w-30 or 10w-30 depending on how cold it gets at your house.

 

Flash, you raise an interesting point regarding the extra stress issue...but for me, it's still a little confusing because, as you know, the 4.0L comes in both the OHV and the SOHC variety, which are very different designs. So there is no pattern or similarity to go by, at least in that sense. Yet Ford does not recommend 5w-20 in either motor.

Is Ford saying then that both the OHV and the SOHC are "stressed out" engines - by design - and therefore they can't handle the thinner 5W-20?

And I find it ironic that the the Ford 4.0L OHV engine, generally known as quite a durable motor capable of a very long and productive life, would be considered "stressed."

 

My father, a master mechanic of almost 30 years, uses Pennziol 15W-40 in everything he works on. He and I both have gotten 200,000+ miles from engines with this formula. For my new truck, I will be using 10W-30 as I feel that 15W-40 will be a bit too thick for winter use around here. Still, I feel the 5W-30 is too "thin" for the best protection, especially in summer months. It works for me past 200K, so it's heavier-grade Pennzoil for me.