How often to change the oil?

I use synthetic oil, and do not worry about how long it sits. I do think that it needs to be started, and let run until it warms up well, to keep fresh oil recirculated from the drain back up into all the engine parts. Without mileage, the age of the oil makes no difference. With synthetic, I plan oil changes closer to 10,000 miles, whenever it is convenient.

Conventional dino oil breaks down over time. That means if you only use your RV a few times some years you still need to change oil about once a year at least. With synthetic oil it is possible to go much longer.

Don't know about your 2007, but for our 2003 E450 Ford recommends their Motorcraft 5W-20 semi synthetic oil. The filter is the Motorcraft 820S. Both available at Walmart.

I change the oil and filter every 5,000 miles, although I have gone over that number somewhat a few times on long trips.

During long periods between trips (mainly Winter) we take a drive to a mall about 20 miles away to give the engine, drive train, brakes and other moving parts some "exercise". IMO regular exercise is good preventive maintenance.

Sealed up inside the motor. not dirty unless it is ran. should last as long as it would in a can on the shelf.

I change mine at 10,000 miles regardless of time. Ford calls for 5,000 and some time interval... so what.
I do not make short trips. Always put away hot. 190k and doing just fine.

At whatever time interval or mileage you would normally become nervous about it, send a sample for analysis. That should give you a good starting point.

Thanks for the replies. I'm just worried about our investment.

I ran Mobil 1 5w-20 about 8 months and then Mobil 1 5W-20 EP 21 months before change both 4200 miles or so and did an oil analysis. Didn't see any issues. I would be most concerned about the cellulose oil filter so am now running a Ford racing filter w/synthetic media on an extended run.

Terryallan wrote:
Sealed up inside the motor. not dirty unless it is ran. should last as long as it would in a can on the shelf.

Not necessarily true.

Part of what contaminates oil is chemical products of combustion and sometimes a tiny bit of raw fuel. Then there is water condensation that results from "winter" temperature swings.

I use synthetic and change on mileage, which turns out to be about once a year. I run it once a month during storage.

BUT.....ample personal testimony exists indicating that it really doesn't make any measurable difference, as long as you don't deviate TOO far from the recommendations.

I do about 9,000 miles a year, and change 2x, usually around now at the start of the season and then about 1/2 way through, targeting never going over a 5k interval. Motorcraft 5w-20 and a FL-820S filter, available as said at any WallyWorld or Advance/AutoZone.