winter storage facts vs fictions

[DannoXYZ]

Here's couple of ideas I've seen floating around:

"Acids from combustion will damage engine, so should change to fresh oil before storage"

There's thing in O-chem known as acid-base buffer that's used in oils. It maintains target pH even when additional reactants are added to mixture. During oil-change interval, hundreds of pounds of acids are added to 4-ltrs of oil, yet pH barely changes from beginning to end. IF acid from combustion is present from combustion, it's always in touch with any engine parts that has oil-coating. So does it matter if exact same amounts of acid is flowing through engine or just sitting? What about the 23-hrs/day that acid is already resting against your engine parts when car's not being used? I want to see test data showing pH levels increasing during storage and eating up engine parts.

"Contaminants in suspended in oil will fall out during storage and settle at bottom of pan and settle in pockets of engine and stick. Given enough time, contaminants will become semi-solid allowing bits to break off and circulate later when engine is started."

Has there ever been any peer-reviewed studies to show this? Actual before & after storage examinations showing what kind of contaminants these are and how solid they get? What about oil filtre? Some only filtre down to 75 microns while others down to 20 microns. How does type of filtre used affect these clumps of contaminants before & after storage?

 

[eljefino]

A lot of oil changes are done based on "feels". IE it "feels" good putting my camaro up on blocks with a fresh oil change.

What happens when Spring comes around? You fart around misfiring and re-tuning everything, dumping fuel into that fresh oil.

Park it with "whatever" oil. If your oil was so bad it's causing internal corrosion, you should have changed it 1000s of miles ago.

 

[dnewton3]

That's not near as interesting as a member who's been here since 2013 and yet has only 3 posts.
Talk about restraint!

 

[DannoXYZ]

That's not near as interesting as a member who's been here since 2013 and yet has only 3 posts.
Talk about restraint!

heh, heh.... I originally joined when I had my tuning shoppe. Specializing in Porsche Turbos, mainly reprogrammed ECU chips and dyno-tuning. Then I got bored with it and went motorcycle racing instead! Question came up around discussion with some other racers about winter-storage of bikes where it's not uncommon for them to sit 3-4 months at time. I've done pre-storage and post-storage oil-changes and never noticed any differences. Only problem I've ever had was on carbureted bikes where petrol dries to plastic sludge and clogs passages all way from tank onwards. (

 

[k1xv]

Fuels, both gasoline and diesel, have much less sulfur than 30 years ago. The less sulfur in the fuel, the less acid produced in combustion. The total base number in new motor oil is less than it was years ago, because there is less acid being made that needs to be neutralized. My Corvette is only driven about 6000 miles a year, So it only gets an annual oil change, usually in the Fall.

 

[ATex7239]

Due to the military (training, work ups, developments, etc.) and a decade of field work I had several vehicles that set for long, and often unpredictable, amounts of time. I never did anything special to them beforehand. Parked them as they were, let them sit there, and did whatever I had to do to get them going once I returned. One of those vehicles I know for sure ran for at least another 10 years after I was finished with it.

 

[RazorsEdge]

Everyone has their own routine and reasons.Pick one that works for you and stick with it.

Just an example:
I drain the oil in the lawn tractor in the Fall. I install a new spark plug, air filter and oil around April. Works for me

 

[weasley]

The first thing to address is that oil is not an aqueous system, so the concept of "pH" does not apply. In an engine oil there are numerous acidic species that can be problematic. They may exist as an aqueous droplet of a strong acid within the oil or as a solubilized (or partially solubilized) organic acid.

The acids largely come from two sources:

1. combustion products of fuel. The result of heating sulfur and nitrogen with oxygen and water, leading to sulfurous and nitrous acids. Strong, aqueous acids. These can be neutralized by alkaline materials in the oil, held in micellar suspension by the detergents - usually calcium carbonate. It is possible to have acidic droplets and alkaline droplets dispersed in the oil that haven't interacted. Strong acids corrode readily.

2. oxidation (and sometimes nitration) products of oil as a consequence of heating the oil in the presence of air. Organic molecules that form weak acids. Can be neutralised by the above alkaline materials or by weak organic alkaline species in the oil formula. Weak acids have limited potential to corrode.

Acidity in the oil is measured by TAN; total acid number. Usually tested by potentiometric titration. Alkalinity is measured by TBN; total base number, tested in the same way. Both are represented by the unit "mg KOH/g" which is a comparative unit - there is no KOH in the oil - the units represent the TAN by how much KOH would be needed to neutralize it, and the TBN by the equivalent amount of KOH. Unlike pH, which is a single number for a given solution, you can have both TAN and TBN in the same oil sample - their results are effectively independent of each other, although generally TBN falls as TAN rises.

A used oil is a complex mixture of chemicals, including the acids mentioned above. If left long enough, the oil can continue to slowly oxidize, caused by the reaction species in the oil (including free radicals) and a lot of time. This is why some very old barn-find engines have a thick, or even gelled or solidified oil in them - it almost certain it wasn't put away like that. However, even if there are acid droplets in the oil, they may be held away from the metal surfaces by detergents, dispersants or other surface-active species, or by any tribofilm that may have formed (eg from ZDDP).

Whether or not any given sample of used oil contains enough of the right acids to corrode any given engine depends on various factors. How used the oil is. What formula the oil is. What the storage conditions are. What materials the engine and its components are made of - for example copper is a good reaction catalyst, as are iron filings. What we do know though is that a used oil is more 'acidic' than a fresh one, so replacing the oil before a long storage will always be a better bet, even if the used oil may or may not be corrosive over the storage period. Unfortunately an engine in storage is not a scientifically-controlled experiment, there are way too many variables, so predicting this is effectively impossible. However, 3-4 months is not a long storage time - my bike often sits this long over the winter and I have no qualms about leaving the oil in it.

 

[Ride_Red]

I'm usually a "change in the fall" guy. I'll start the engine and let it warm up and mix up, then drain. I feel better about having fresh oil in my engines when they are going to be sitting for a long time.

With that said, I do oil changes every two years on my lawn mower. I'll sometimes carry my motorcycles OCI over the winter because of low mileage.

If I was storing an engine for an extended time, I would make sure to change the oil. For example, I change my generators after they have been used because I don't know how long they will sit until they are called upon again.

 

[STW]

That's not near as interesting as a member who's been here since 2013 and yet has only 3 posts.
Talk about restraint!

Wait.... WHAT?

 

[gfh77665]

I change oil before storing. That can never hurt, and might help if the old oil is spent. It also helps keep easy track of when it was done.

Of far greater concern is the fuel. Thats priority #1.

BTW never store anything on blocks. Ever. Suspensions were made to be weight loaded.

 

[slomo]

Due to the military (training, work ups, developments, etc.) and a decade of field work I had several vehicles that set for long, and often unpredictable, amounts of time. I never did anything special to them beforehand. Parked them as they were, let them sit there, and did whatever I had to do to get them going once I returned. One of those vehicles I know for sure ran for at least another 10 years after I was finished with it.

I can attest to this. Army NEVER changed anything. We would supposedly send samples to the lab????? Never heard back about changing any fluids out ever.

 

[Nesterenko]

petrol

I didn't think a guy from Santa Barbara would use the word petrol.

 

[slomo]

I didn't think a guy from Santa Barbara would use the word petrol.

What a knee slapper.

 

[bobdoo]

During oil-change interval, hundreds of pounds of acids are added to 4-ltrs of oil,

Hundreds of pounds of acids?

Call me dubious.

 

[Nesterenko]

What a knee slapper.

Well the guy that said it, (OP) in fact liked it so that should quash your sarcasm.

 

[kschachn]

Hundreds of pounds of acids?

Call me dubious.

The whole post is a dumpster fire.

 

[Sumboodie]

Fuels, both gasoline and diesel, have much less sulfur than 30 years ago. The less sulfur in the fuel, the less acid produced in combustion. The total base number in new motor oil is less than it was years ago, because there is less acid being made that needs to be neutralized. My Corvette is only driven about 6000 miles a year, So it only gets an annual oil change, usually in the Fall.

Interesting enough, I just cleaned a diesel boiler and it had yellow residue yellow from the sulfur in the fuel...

Huh, pic doesn't show well... taken at night. That flakey stuff was all bright ylow.

 

[k1xv]

Interesting enough, I just cleaned a diesel boiler and it had yellow residue yellow from the sulfur in the fuel...

Huh, pic doesn't show well... taken at night. That flakey stuff was all bright ylow.

View attachment 250204

I don't know when it was last cleaned. The 15 ppm on motor diesel fuel was imposed, in part, to protect emission systems that do not apply to stationary boilers. I believe in most places in the USA, the boiler fuel #2 is dyed 15 ppm motor fuel, but legally can be 500 ppm. In any event, I was talking about the fuel used in reciprocating automotive engines.