Oil change

if the car hasn’t been driven since the last oil change. does the oil have to be changed when the next oil change date arrives?

Based on the information provided I’d say no, but the oil should be changed once per year even if the car is driven little or no mileage.

Year, make, model, etc, might elicit a different response.

To be honest, I’d worry more about the gasoline in the tank than the oil in the engine.

With that type of driving(lack thereof) I simply would never exceed 1 year. 6 months is optimal but 1 year is reasonable.

I’m curious. What is the technical basis for this? Does oil shelf life make a big difference? Are oil cans marked with a use by date?

When was the last time you saw an oil can? Oil in a bottle (or can) will keep virtually forever. There is no expiration date.

Oil in the engine, however, collects byproducts of combustion (if the vehicle is driven) and moisture from condensation (even if the vehicle is not driven), among other things.

You change the oil to remove the contaminants.

I don’t recommend letting a vehicle sit, un-driven, for months at a time, but if it’s necessary for some reason I would still change the oil once a year.

A vehicle that sits for a long period will have other problems. The oil may actually be the LEAST of its problems.

I’d like to respectively reopen the question my2cents raised.

If you change the oil in a car, and then don’t drive it for a year, the contaminants in the oil will be due to condensation - and a good road trip will easily burn them off.

After the road trip, how will the resulting oil quality be inferior?

It probably won’t be inferior at all, and, yes, you could probably get away without replacing the oil. But then the question becomes, just how long are you willing to leave the same oil in the crankcase? Two years? Three? Indefinitely?

If the oil is OK after one year, wouldn’t it be OK after two or three? Yes, it probably would. Changing the oil once a year is just cheap insurance. Nothing more.

As I said, an unused car is likely to have more important issues than the oil. The question, however, was about oil, and I, personally, wouldn’t want to leave the oil in the crankcase more than a year. You, or the OP, can choose to do differently with your own vehicles.

I’d use the year-old oil I drained out of my unused car (in this hypothetical situation) in my lawn mower or snow blower, however, because there wouldn’t be anything wrong with it.

When was the last time you saw an oil can? Oil in a bottle (or can) will keep virtually forever. There is no expiration date.

In the can or bottle yes, but in a car it is subject to condensation exposure to air etc.

In this specific case if the car was not even started (not OP wrote driven, not the same thing) and assuming it is not going to be put back in service, that I would drive it for a few weeks and then change it as it may pick up some rust and such from the time it was in storage.

Oil, unlike gasoline, does not “GO BAD” just by sitting there. If the car is driven and the oil changed and then parked, the oil will stay fresh for a very long time. As pointed out, some condensation is all that will settle in the crank case and that will evaporate once you warm up the car.

I agree that the gas in the tank is a bigger worry.

Boat owners may operate their boats only once a year, and sometimes not at all. They don’t change oil if the boat is not used. It makes no sense to dump perfectly good oil and a new filter with no miles on it.

Some very slow moving cars sit on the dealer’s a year or so. I don’t see the service department bring the car in for service with 3 miles or so on it.

Clearly, this is a special case, and an oil change every 2 years might be more in order.

Finally a situation where you can extend a oil change interval, unfournately it involves not operating the car.

How many miles were on the oil when the car was parked?
How many miles are on the engine?
How long was it parked?

I’d want to know more. If the oil was already overdue, the engine was old and tired, and it’s been sitting for a long time, the oil will probably have been sitting there diluted by blowby…volatile compounds…and I don’t honestly know the effects of that on oil when the two are together for a long time. If this is the case I’d want fresh oil in it.

Oil’s cheap. If in doubt, I vote to change it.

Most of the US Navy steam turbines used a 2190 TEP oil and NEVER changed it…oil does not wear out…only becomes contaminated and then loses it lubrication properties. You will most likely not have any problem with the oil sitting in an engine but you might have a rust problem with any metal prone to rusting if you dont turn the engine over and circulate the oil periodically. Gasoline will stay “fresh” for close to a year so dont worry about that too much. Your brake rotors will rust dramatically however and wear your brake pads down more than usual until you get the rust off the rotors.