How long can I keep oil in a car that I rarely run?

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greymouser7

greymouser7

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I know that oil that is left for several years becomes acidic-not sure why but I have a back up to my daily driver and I start the motor and run it more than twice a month but the wife might not every time I am deployed for three months (usely slightly less than twice a year) .

I have had the car for two years-dad's old daily driver.
Do I need to be concerned about the gear oil in the trans-it's possible that it has not ever been changed since 1991.

My daily driver has 317k miles but the motor has been replaced with unknown miles-runs like a top...This backup car that doesn't get driven too much is the same scenario as just mentioned. The oil isn't brown anymore but not really black. Should I just put synthetic in there to last longer? I did put premium gas and fuel stabilizer in the tank.

Thanks for everything-I love this community!
 
i wouldent worry about the tranny or gear oil but i would like to hear opinions on the motor oil i did read sumtin about once a year on rarely driven engines ... jimjim
 
if you are starting it up from time to time and keeping it circulating , it should last for the life of the car. i would guess? i dont think oil has a shelf life. i kept the same oil in my super bee for over 9 years, it never got driven.
 
What kills engine oil is moisture buildup. It's not a problem in one that's driven daily, even in humid climates. I'd say change it twice a year if it sits long periods. You can change to synthetic, but you might find that you have more spots in the driveway than with conventional. The synthetic tends to flow so well it finds leaks where carbon based oil will not. I wouldn't change to synthetic for the reason you're asking.....carbon based oils have come a long way. You're probably ok just doing it the way you're doing it. As long as the car is started and driven twice a year, but driven up to temperature for a good while, it's probably ok.
 
I think the key would be getting the engine hot enough to evaporate out all the moisture. Starting the car cold to move it in or out of the garage would be bad. But if you always drive it far enough to reach full temp the oil should last a long time. Same thing for the exhaust system.
 
It's not just moisture, it's ACIDS and other reactive chemicals that are products from combustion and blowby.

I'd change it once a year no matter what.
 
If you're not driving it much, there is very little in the way of combustion contaminants getting into the oil. If you warm it up to full temp when you do run it moisture will not be a problem.

That said, my Mopars spend the winters mostly sitting with occasional warm-up drives maybe once a month, weather permitting. The oil in the Chrysler is now over three years old and still looks good, no issues. It's getting changed this summer and probably has at most 2k miles on it over those 3+ years. No worries.
 
For storage of cars, you're looking for an oil that has a high "cling" factor. Something that is going to leave a lasting film on the rockers, cylinders, and bearings, etc. THAT'S how you control moisture, especially when you're deployed.

Some people prefer diesel oils because of their high cling factors, others like to add a can of STP to an engine and then drive it for about 30 minutes before parking it for long term, and then there are those who prefer heavier single weight oils.

In any case, you'll need to research the oil that has the best properties to cling to the internal parts the longest.
 
I've heard this question before but it was in reference to vehicles under warrenty. "Why do I have to change the oil regularly if the vehicle is never driven ?"
The simi-complicated answer was, 'Oil has a shelf life while closed up in a bottle but its not closed up in an engine. It's going to react to metals and the atmosphere a lot differently than it does to the bottle. Plus there is always comtaminated oil remaining in the engine. Impossible to drain it all out.Went on and on to convince the old chap that not changing the oil as dictated would void the warrenty and/or why. Even compared the oil to dirty drinking water.
I've also heard once you change to synthetic you cant of shouldn't go back to conventional. I dont know if that is true.
 
It is not all that much $$$ to dump it every now and then......
 
inkjunkie said:
It is not all that much $$$ to dump it every now and then......
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Right. Except that the difference in price between the cheapest and most expensive oil can be pretty steep and the difference between now and then = 3 years (in my case). It helps to define your terms.

There is no issue with going back and forth between synthetic and conventional oils at will. In the case of my Chrysler which I mentioned earlier, I ran an expensive Shaeffer's 9000 HDEO for the past three years, and started a cleaning cycle with an oil treatment in that a couple months ago. I will run a relatively cheap conventional (Catrol GTX) oil over the summer to rinse that out and go back to the good stuff in the fall.

For maybe 4 years, next time. You may choose to just dump it every now and then. It's all good.
 
In storing cars, it's the price of the oil that counts. It the oil's ability to "cling" to the parts for long periods of time.

It's the coating of oil that stays on the parts for long periods of time that keeps everything from rusting and seizing.

With the flow factors being so high on synthetics, I can't see them being any good for sticking to the internal parts of the engine for extended periods of time. Synthetics are formulated to flow freely and quickly and completely. They might have some residual properties that allows them to stick to the parts for a short while, a few hours, or days, but you're looking for something that will last for months.

I suppose you'd have to research some of the sticker oils, or perhaps there is even an oil that is blended for this purpose.
 
Hell if you want something to cling, just put chainsaw bar and chain oil in it. lol
 
340-4spd said:
Right. Except that the difference in price between the cheapest and most expensive oil can be pretty steep and the difference between now and then = 3 years (in my case). It helps to define your terms.

There is no issue with going back and forth between synthetic and conventional oils at will. In the case of my Chrysler which I mentioned earlier, I ran an expensive Shaeffer's 9000 HDEO for the past three years, and started a cleaning cycle with an oil treatment in that a couple months ago. I will run a relatively cheap conventional (Catrol GTX) oil over the summer to rinse that out and go back to the good stuff in the fall.

For maybe 4 years, next time. You may choose to just dump it every now and then. It's all good.
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Very true, sorry about that....
 
tiltsix said:
I change it in my Dart every 6 months,it probably doesnt get 3000 miles a year.
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About the same mileage here-around 3,000-and I change the oil and filter 3 times a year. Right about now, then end of summer and then the day before it gets driven 30 miles to the storage building, around Dec 1st

I sometimes get on the engine hard and 3.91's gears means lots of rpms on the expressways. Just cause the mileage is low doesn't mean a whole lot.

Maybe the amount of fuel the engine burns would be better to go by then how many miles ?
 
You could use Lucas oil treatment. It will stay on parts longer between starts. It costs so much though, that you might as well just change oil routinely. I change oil in all my cars at 3000 mi. or 6 mos. You'll have more trouble with old anti-freeze.
 
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