Just did my first oil change with about 1100 miles on the engine. Maybe a bit more. I'm not sure how many miles Proffitt put on.
It runs super clean, I haven't seen a hint of smoke. Maybe just a fuzz of hazing after engine braking, then getting into the throttle hard. Like decelerating to make a turn onto another road, then accelerating aggressively. But very short lived, and not much.
I am surprised at how dark the oil is after so few miles with how clean it runs. There was some ferrous goop on the magnet. Nothing out of line in my opinion, and no glitter. I don't have a way to cleanly cut the filter open to inspect that. I also couldn't get it loose by hand, and went for the trusty "stab a screw driver" method. So it wouldn't have been a great one to cut open anyways.
I really should invest in some filter wrenches.
In normal Cummins fashion, the drain plug just requires a 3/8" ratchet. It is o-ringed, versus a crush washer, I like that as well. Plug is right in the bottom of the pan. My stupid Ford pickup, it's mounted on the side, and I get oil everywhere when I change that.
PRLC puts the filter in a great spot. Super easy to access. It's vertical, and won't make a giant mess when changed normally. Stabbing a hole in the bottom doesn't count as normally....
Right off the bat a couple of observations about the 2.8.
It vibrates more than I anticipated. I hadn't put any thought into it prior to getting behind the wheel. Oddly enough, most of the engines I've owned have been straight sixes. 2 Ford 4.9's, a Datsun 2.8, 2 Cummins (B & ISB), and two Toyota sixes. 2F & 1FZ.
I'm used to inline sixes, which are always smooth runners. Straight 6 and V12's are the only engines that naturally balance?
A four cylinder is never that smooth, and I've never driven a diesel inline 4, so more an adjustment of expectation than anything. I have ran plenty of skid loaders and telehandlers with inline fours, and really should've known better.
Power is hard to explain. It's got plenty of torque. But it definitely does not like being lugged. It is not happy when presented with a high load, and a high throttle setting. I've been shifting around 2600rpm in normal driving conditions, and that seems about just right. The H55 has some weird gearing. 1st to 2nd is close in ratio. 2 to 3, and 3 to 4 is pretty well spaced out. 4-5 are pretty close in ratio. 4th is 1:1, I think 5th is something like .85:1
Keeping the micro Cummins in a happy rpm range takes some practice. My rig with two people, no gear is 4800 pounds, I just weighed it this past week. It's aerodynamics are absurd. AND, you have got 170hp, with a skinny powerband to make it all work. So I'm not surprised. What I've noticed is it likes to be above 1800 rpm, and above 3000 rpm is a waste. I've spun it past a 3500 a few times, most just to ring it out a bit. I believe a properly broken in engine sees a multitude of loads, and heat cycles. Some long duration, light loading. Some short duration high load so temps spike.
In low range, everything changes, it's just great with the limited trail time I had with her.
Mileage is less than I thought. I was hoping to see mid twenties, expecting to see 22-23mpg. Wish in one hand, poop in the other, right?

The handful of fills have been just under 20mpg 19.5, 19.2, 19.75 I think were the numbers. Today I got 20.75 when I tanked. Which brings me to my next observation.
I think, (not certain), Cummins runs a break in tune. At around 45 hours of engine time, it changed. Nothing huge, nothing significant. It seems to have a bit more power, and to be a bit smoother running. Now while idling at a light, my mirrors are no longer fuzz, and I can actually see out of them. And, the last fill was better mileage.
The internet is strange, I've read on here guy's reporting much better mileage than I'm seeing. Which could be a multitude of things. I use the accelerator more, I just drive differently, or have different conditions. Fuel quality varies wildly. Or, somebody spent a buttload of money and effort on something, and they're fibbing the facts a twinge so they feel less like an asshat.
Overall, I'm thrilled. I made the right choice, and I'd do it again. It's a great powerplant for the FJ40. I fricking loved it off road, and on road it probably actually exceeds my expectations. I still avoid the interstate, but 70mph is easily done when I need to. 80 miles and hours is doable too, but I don't want to die that way. Plus, I can safely pass on a two lane when needed.
I'm likely talking out my ass, (while simultaneously justifying my own gaping hole in my checking account...), but my gut feeling is I couldn't get a 2F to do what that itty bitty oil burner does. Even if I pumped in the same dollars into a 2F, I wouldn't have the power, the delivery, or the range I do now. I would like to drive a 40 with a built 2F. Mine is/was no comparison, it was very tired.
Pro tip: neodymium magnet on the side of the fuel filler well holds the cap nicely.
I was setting it on the gutter, but I don't care for setting anything on paint.
If it doesn't work on your Aqualu tub, try contacting a sorcerer.