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As usual, my 2005 F350 is about to go into winter storage by the end of this month or before snow flies. I keep it out of the salt. I do 5,000 mile interval oil changes, and my truck is indeed just a few hundred miles from hitting that interval. This time is just oil; did fuel filters as well last time. I already have 4 gallons of T6 5w40 and the OEM filter on hand. The question: do the oil change now right before 4+ months of storage, or wait and change the oil right at the start of bringing the truck back out of storage?
I would do it now. The old oil has acid built up as well as some water. if you get it hot before the change, you will cook off the water but not the acid.
I would go with change it before parking as well - something about it sitting with fresh oil and full add-pack over winter would make me feel better...
If you follow "Used Oil Analysis" data, you wouldn't be all that concerned over a synthetic oil at 5000 miles being "acidic". I have NEVER seen a bad TBN (Total Base Number) or TAN (Total Acid Number) after such low mileage. They show PLENTY of protection against low pH exposure on the oil analysis for synthetic diesel oil.
The 6.0L community typically changes oil more to protect against STICTION then degraded oil additives.
The obvious exception is when people severely overheat their engine ........
Frankly speaking, it really won't matter either way.
The only worry about a vehicle being left unused for months is the accumulation of moisture that happens from humidity and the day-to-night temperature changes. When it is running regularly, it can burn off any moisture. You can avoid circulating oil with some (who knows how much) elevated moisture by changing out the oil AFTER storage ... and before the start-up. That is all I was thinking about.
I would change it now. If you don’t, it is like putting your truck away with dirt and salt on it and cleaning in the Spring. Well maybe not that bad but you get the point.
I change my Royal Purple Super Duralec 15W-40 synthetic diesel oil every 10K miles. However, I drain out 2 quarts of oil and add 2 quarts of Seafoam (15% oil capacity) for the last 100 miles. Before I drain the oil, I start the motor and bring it up to temperature. I then drain 7 quarts of oil out through my Fumoto valve while it is running, then shut it off and let the rest drain. This make sure that max contaminates are suspended in the oil as it drains.
I also use a K&N reusable SS oil filter that I remove and clean every 2,500 miles with Seafoam.
My X is a 2004 Limited 4WD with 175K on the clock.
I store my truck every winter. It always ends up that the oil change is due (5000 km on it) when the truck is ready to go away. I park it with " dirty " oil . Come spring it get it warm and drain it then. I have no oil analysis to say which is the best. But I wouldn't want to run my truck in the spring after it's been sitting there for months collecting moisture. And I'm sure not spending $150 on new oil in the fall, and another $150 in the spring.