Question Changing engine oil before or after storage

[MapNerd]

If oil contains acid (news to me, but okay) I would presume it has to be a very mild acid. No manufacturer of sound mind would allow for any oil with a strong enough acid to do damage to internal components to go into their engine - regardless of oil age and similarly no oil manufacturer would produce something like that without using some pretty obvious warnings on their packaging about the products intended use.

But let’s say the acid is there. Surely it’s not harmful when the oil is fresh right? So is the logic that the oil becomes more acidic as contaminates increase? I don’t buy it. Under that logic, you should store with the oil drained which seems like an awful idea.

 

[Joe Hogan]

Typically the acid in motor oil comes as a by product of combustion. The Sulphur content in fuels, currently limited by EPA regs, contaminate the oil via blow by and residue on cylinder walls.
The Sulphur combined with moisture from the air intake creates sulphuric acid. This along with other contaminants are collected, hopefully in suspension, in engine oil. This is one reason for regular oil changes.

Sulphur in Fuels EPA Standards for Fuel Sulfur | US EPA

 

[AbdRahim]

I asked at the light truck place that services my gas powered chassis. His thought was when taking out of storage. I was doing both. An extra 7 qts of oil a year is alot cheaper than any long term damage.

 

[Gizmo]

My engine manual on my Cummins states to change every 15,000 miles or 1 year. We store our Nov and Dec then head south in Jan for the rest of winter. We normally travel 10,000 to 12,000 miles per year and even in 2020, we logged close to 12,000 miles. So every Nov we have Freightliner change all filters and oils and do a safety inspection preparing for the next year's travels. This works well for us and we are not somewhere that we are not sure of the quality of service we will receive or how long it will take to get into service. We have built a relationship with our local Freightliner service center. This works for us....

PS In my state to get tags on a 1-ton truck is 1390 bucks to get tags on my 40 foot DP is 299. Switching to the motorhome SO FAR has saved us money because we can get our service is done at Freightliner for 800-900 dollars still have money left over for a few steak dinners. We have had zero engine repairs since we owned our motorhome.

 

[J&JD]

I’m with the camp that changes the 28 qts (good grief!) of oil in the Cummins every year/12k miles only because I’m an anal individual. However, I would be willing to bet that if you only changed the oil every 5 years/60k miles that big old Cummins would be ok, even if you stored it for a year.

Change the oil before or after storage as it’s just not going to make much difference in your engine for the time you will own the vehicle.

 

[Joe Hogan]

Unfortunately many of my engrained thoughts are from many years ago. Thoughts on oil is no different.
Pre Synthetic engine oil, sludge and oxidation/contamination participating out of used oil sitting for extend periods was an issue. Consequently formed sludge in engine oil pans and other parts of the engine.
Back in the 1960s and early 70s when I had the opportunity(?) to disassemble various engines to find copious amounts of sludge build up in oil pans (back when I purchased many used cars for CHEAP) and valve trains from poorly serviced vehicles. That memory has stuck with me.
Now that we have Low Sulfur fuels and Synthetic Engine oils, these issues may be a thing of the past or at least less common.
Next oil change I am going to take a sample and let it sit for 3 months or so to see if contaminates still participate out.

 

[Neal]

Also consider an oil analysis, in fact why not just do that now?

 

[Texas Clodhopper]

Blackstone can tell you probably more than you need to know about your oil.

Blackstone Laboratories Blackstone Laboratories

Learn what's going on in your engine with oil analysis. Our free kits are easy to use and we explain the results in plain English!

www.blackstone-labs.com

 

[AbdRahim]

Unfortunately many of my engrained thoughts are from many years ago. Thoughts on oil is no different.
Pre Synthetic engine oil, sludge and oxidation/contamination participating out of used oil sitting for extend periods was an issue. Consequently formed sludge in engine oil pans and other parts of the engine.
Back in the 1960s and early 70s when I had the opportunity(?) to disassemble various engines to find copious amounts of sludge build up in oil pans (back when I purchased many used cars for CHEAP) and valve trains from poorly serviced vehicles. That memory has stuck with me.
Now that we have Low Sulfur fuels and Synthetic Engine oils, these issues may be a thing of the past or at least less common.
Next oil change I am going to take a sample and let it sit for 3 months or so to see if contaminates still participate out.

In the north country it sits for 7 months.