Thanks for this helpful explanation in great detail, i was entering incorrect subjectTaken from the 2022 Bronco owners manual:
View attachment 4363
A agree with Ford on the no towing or heavy loads on the engine the first 1000 miles, I've even heard higher mileage before towing.
I'm not sure if it's needed anymore, but I also vary the speed/engine RPM's for the first 1000 miles.
For the first 500 miles I take it a step further, once again may not make any difference with the engine but I feel better and I've never had a engine use oil after following these guidelines.
Short trips, constant on/off throttle, less that 30 minutes allowing engine to cool between trips. Gradually increasing max engine rpm over time (once engine has reached operating temp), approximate values below as a general guideline.
0-50 miles - max 2500 rpm
50-100 miles - max 3500 rpm
100-200 miles max 4500 rpm
200-400 miles max 5500 rpm
400-500 miles max 6000 rpm
Not sure if this applies anymore, but the theory is when the piston is under compression/load the rings are wiping the cylinder walls dry of oil, during de-acceleration/coasting the cylinders bores are being oiled. Hence the constant on/off throttle.
The day after taking delivery of my new 1989 Bronco, with a 351 HO, I pulled my boat to the lake ~200 miles round trip and that engine always used a quart of oil every ~1k miles. It's the only engine I've ever owned that used oil, and I had several 351 HO's.