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[jayman]

The Rotella is a heavy duty diesel engine oil. Rated very highly, so is Mobil Delvac 1 5W-40, and the consumer offering Mobil 1 Turbo Diesel Truck 5W-40.

Any heavy duty diesel oil has far higher detergent levels than a regular passenger car oil. Even with extended oil changes, the motor will stay spotless inside

There is some concern that using a HD diesel oil in a passenger car might not be compatible with the O2 sensors or catalyst. For the most part, that's bull. Almost every HD diesel oil I have seen is cross-rated to SM or SL.

I have an '84 Ford pickup at my hobby farm that has been in the family since new. It has *always* run on HD engine oils, usually Delvac 1 or Esso XD-3. Several years ago I noticed a bit of seepage from the intake gasket, so had to pull the intake manifold

Well, one of the bolts snapped in the head, so I had to take one of the heads off too. Note: most Ford's of that vintage set the valve clearance by different length pushrods. Never pull out all the pushrods and throw them into a box. Set up an organizer so every lifter and pushrod will go back to it's correct location

Underneath the manifold was spotless, a bit of film on the EGR passage. Most Ford intake manifolds with the EGR crossover will be so heavily built up after 15-20 years you'd have to use a crowbar to pry the manifold off.

Intake valley absolutely spotless. All the lifters were clean and free moving. Cylinder head spotless too, rockers and springs all clean. FWIW that motor has 530,000 km on it, compression is 125 lbs, with oil squirted compression is 170 lbs

I'm currently using Mobil 1 0W-40 European Car Formula in my FJ, with very good used oil analysis. I wouldn't be afraid to run Delvac 1 or Esso XD-3 0W-40/15W-40 either

The Rotella should work fine for you. There will be minimal fuel economy difference. I ran Esso XD-3 15W-40 in my Prius a couple of summers ago. Compared to Mobil 1 0W-30, at most 2 mpg less