Originally Posted by Studiovette
Thats off some website Ford has...did you actually see that in the manual? Mine is a 2018 V-10 e450 chassis and 6 months or xxxx miles (mileage depends on usage...normal or heavy)
Leaving old oil in the crankcase that has acid from combustion is not good for the engine. That's why the 6 months is more important than the miles. I doubt many will see 7500 miles in 6 months on a motorhome or even 5000 for that matter.
Even when I get my Jeep oil changed the dealer puts a sticker on the windshield that says oil changed needed in xxxx miles or a date which is 6 months from last oil change.