B-STOCK

I always change my engine oil before the car go's in Winter storage. Now I hear folks say change when it comes out. Have I been doing it wrong for 60 years.

A Marsh

One of the jobs of all the stuff added into oil is neutralizing the acidic byproducts of combustion. As oil is used it becomes more and more contaminated with these acidic byproducts.

I think the best guidance is to have fresh oil in the engine during the time it's sitting in storage.

I've been riding motorcycles for years. I've always put them up for the winter with fresh oil in them. This is based on guidance I've received from a number of sources over the years.

That's only my opinion. I'm sure others disagree.

craig-o

I have always done fluid changes before storage - for all my seasonal cars and my boat. The reason is to have clean, fresh fluid with optimum corrosion resistance and minimal contamination. Also a full tank of fuel with fuel stabilizer to minimize the air space in the fuel tank and potential for water in the fuel due to condensation.

What would be the rationale for changing it at the end of storage?

A Marsh

I agree.

MY03C5Z

Some people think because there's a lot of moisture that accumulates in the crankcase from sitting over the winter. Mine sits in an insulated garage that doesn't get below freezing and I have always changed my oil at the start of winter before it sits. When you fire it up and drive it the first time any moisture in the crankcase is going to be gone after the first drive anyway. Much better than letting the engine sit for 3 months or more with used oil IMO. I've read that some here will change before and after the winter, which is a bit crazy to me.

B-STOCK

Glad to hear I was doing it right all these years. Putting it away clean always made sense to me. Did three cars of my own today and a friends. He had not changed his oil in a couple of years and the filter was a bear to get off. I have a wide variety of quality filter wrenches but no dice. Had to go through the filter with a large screw driver to loosen it enough to get a good crush on it and finish it with a slip wrench oil filter tool. There is my new reason to do it once a year at least. I only had to remove a filter like that once in my life and that was in the early 60s. At least this time I had the car on my lift.

Brock63

changing after winter is important as your engine will leach out all of the contaminants and stuff while sitting..... that being said this is how I treat any vehicle not being driven at least once a month and until it gets FULLY up to temps.

I change to fresh oil right before storage using cheap syn blend oil.......protection but not top of line.

Then for Spring I would warm up just enough to get oil out for change...and put in the good stuff. Your motor will leach out contaminants during time it sits idle...just like you can shoot a weapon quite a lot and it is hot then clean it and two weeks later find it dirty as the grime is pushed out into the lube you put on weapon.

3boystoys

I barely put 3K miles a year on mine, I change in spring with fresh synthetic-once a year no problems.

SPDaylightFan

I never liked the idea of my Vette sitting there all winter with dirty oil in the crankcase. All that dirt, grime, and other nastystuff just eating away....... I like to know it is clean.

3boystoys

Think your WAY over thinking this. It's the same oil you drove the car with last.

Cosmo Kramer

From what I've read, used oil contains small amounts of carbon deposits from the comustion cycle (blow by.) If the oil sits for a period of time, the deposits will settle out and cause slug. If enough slug accumulates, a chunk could dislodge and plug either the oil pump or an oil passage way thereby causing a potential engine problem or failure.

To test this theory, I changed the oil on my Corvette last fall (the oil only had 3K miles on it.) I then put a quart of the old oil into one of the new, but empty containers and let it sit over the winter. When I poured out the oil in the spring, slug had accumulated in the bottom of the container. If I multiply the slug by five (number of quarts) then multiply by, say, five again (number of years of storage,) the amount of slug accumulated could be significant.

Although not apples to apples, I rebuilt a '70 L46 (350/350) engine a few years ago and could not believe the amount of slug that had accumulated in the oil pan. You could take a putty knife and scrape out chunks of slug.

3boystoys

That's NOT how SLUDGE forms, SLUDGE forms from oil getting COOKED. AGAIN, your propagating an Urban legend with no basis in FACT.

Cosmo Kramer

3boystoys...........I stand corrected. Thank you.

Nevertheless, that "stuff" in the bottom of the used oil container (from my garage experiment) was nasty and looked and felt exactly the same as the "stuff" in the bottom of the oil pan in my '70.

Sterling04

Why not stop the concern over when to change the oil and change it before and again when taking it out of storage. The cost of oil and filter is less than $50. I'd say that was cheap insurance for an engine that cost over $10,000... I've owned motorcycles and race cars and now Corvettes. All expensive toys. An oil and filter change is a lot cheaper than a re-build. Just saying! It's all up to you and your sense of well-being.

Moto One

Hey, Just drive your poor Corvette every now and then, I live in Snow Country, and I manage to put two the three thousand miles on it every winter... Change the oil at the recommend intervals or when ever you feel the need.

Just drive it.

Mark.

rt1970ls6

The following (in quotations, is quoted from SynLube, an oil "expert":

"There are different "types" of sludge, they are of different appearance ranging from light brown to opaque black, they range from semi-liquid to solid, and they can be formed by different chemical reactions.

Since any sludge is formed primarily from the engine oil, the oil itself appears to be at fault. Actually the oil is the victim of mechanical and chemical attack.

The formation of sludge is a very complex interaction of components which include mechanical and thermal stress and multitude of chemical reactions.

Although there are thousands of documented engine failures in the field, not a single research chemist has to date succeeded to create a "synthetic" sludge under controlled laboratory conditions. The real life conditions are therefore so complex as to be virtually impossible to duplicate in laboratory, yet hundreds of engines all over the world fail daily due to sludge formation.

While some engine types are more prone to sludge formation, the fact is that only very small proportion of the "affected" engines actually fail in service.

For example out of the over 3.3 million Toyota engines that are "affected" only about 7,000 of them have had serious failures. That is 0.2% or about two failures in 1,000 engines.

Sludge in gasoline engines is usually black emulsion of water and other combustion by-products, and oil formed primarily during low-temperature engine operation. Sludge is typically soft, but can polymerize to very hard substance. It plugs oil lines and screens, and accelerates wear of engine parts. Sludge deposits can be controlled with a dispersant additive that keeps the sludge constituents finely suspended in the oil.

"Black Sludge" is defined as thick to solid material with low water content, of dark color, light oil insolubles, and typically found in rocker cover, cylinder head, timing chain cover, oil sump, oil pump screen, and oil rings in variable quantities."

Now, since oil does not "age", or get too old, it only gets dirty, why do manufacturers tell you to change oil every XXXX miles OR every XX months? If a car is not driven, no combustion by -products or blowby contaminates the oil, right? The inside of the engine is covered with oil, so nothing rusts or corrodes, right? The reason to change the oil every few months is simple. The same thing occurs when items, such as rubber products, age. The culprit is time, environmental temperature changes and condensation.

As SynLube clearly stated, "Sludge in gasoline engines is usually black emulsion of water and other combustion by-products, and oil formed primarily during low-temperature engine operation." Water - condensation. And low temperature - winter. The heating and cooling of any machine that occurs at temperatures below the dew point create condensation - water vapor in the air inside the engine- condensing inside the engine and being in droplet form inside the engine. Rarely will it completely evaporate, unless some form of heat and/or ventilation occurs inside the engine. Therefore, if you store an engine in the fall with "serviceable" oil in it (not so dirty it is well beyond need of changing), then if you change it in the spring, first thing, (warm the engine prior to changing) any condensation formation will come out with the oil.

As another poster stated, you could change it before storage & after storage, no harm done.

Fast one

I change the Mobil 1 when the car tells me to which is around 10% of oil life. The engine has 116,000 miles on it and it's been stored six months of every year since new; I've never seen any sludge buildup.

rt1970ls6

As the SynLube article stated, sludge formation is very complex. It doesn't always occur. Particularly if you don't do short trips in cold weather, run the engine at excessively low operating temperatures, etc. Driving regularly, in warm weather, for more than a few minutes and regular oil changes (like you do ) is the best way to prevent sludge. I am no chemist, I am an engineer, but your best source of information on engine oil is from oil manufacturers (Castrol, Valvoline, Pennzoil, Quaker State, Mobil, AmsOil, etc.), and the American Petroleum Institute (API). These guys are in study and research continuously. A wealth of knowledge. Much better than opinions from people with no background in petroleum sciences. Oil is like anything else, predicting how to avoid bad outcomes does not mean bad outcomes are certain if you do differently.

Cosmo Kramer

"Sludge in gasoline engines is usually black emulsion of water and other combustion by-products, and oil formed primarily during low-temperature engine operation."

So, sludge is not formed by "cooking" the oil, but rather the opposite. Interesting.

rt1970ls6

I had done research on engine oils when I was a design engineer at a heavy equipment manufacturer years ago. Lots of things about oil were not as I had heard in the past.