Overdue Oil Change and Sludge, safe to drive after oil change?

Hello. My son has a 2018 Nissan Altima SV and it had some work done at the dealership after an incident and he thought the oil was changed when it was there, well the low oil pressure light came on and so he called the dealership and found out oil had not been changed. He took it to Wal-mart for an oil change a day or so later. It hhas been about 1.5-2 weeks since then. The low oil pressure light has came on a few times since then and the dealership said to just bring it in next week. Yesterday the light came on and stayed on so he didn’t drive it anymore i checked the code and it said P0015 Camshaft B position. I googled and read multiple things can cause that code, so had a mechanic friend of mine come take a look. The dipstick was dry. He said Wal-mart probably never changed the oil, when he drained it, the oil didn’t even fill a gallon jug up halfway and it was black. He said there was some gunk under the oil cap also. We put in Mobil 1 synthetic and changed the filter. The light is off now. Is it safe to drive? I have been reading for hours and not sure if he needs a flush or if the new oil will clean up any possible buildup, just change oil more often or what. He is is a young adult and does not live at home so sharing a car is very inconvenient, especially since we both work 45 minutes away and work opposite schedules. Any advice?

Yes it is safe to drive . As for engine damage that is the question . Does your son not know how to check the oil level or just does not do it. The dealer will charge 100.00 to 150.00 just to look at it.

I would just drive it and check the oil level every morning for a couple of weeks . If the level stays the same then check every 2 weeks providing the oil light does not come on.


Agree with Volvo. I believe I’d skip trying any flushes. Just try to remove the sludge over time using synthetic oil and changing the oil more frequently. I’d probably do 5k mile oil changes. Check the oil level religiously and hope for the best. If the light comes back on, take it to a good shop for diagnosis.

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He should know how to check it. Ive showed him how to change radiators, thermostats, and a few other things on a jeep he used to have. I actually saw him under the hood Thursday morning and he said he checked it and that it was fine. It was at 4:30 in the morning after working his first 12 hour night shift, so idk if he was sleep deprived or maybe he couldn’t see well because it was dark outside or what. I am going to make him check it in front of me to see what exactly he looked at.

I’m no expert, but I personally wouldn’t wait much past 1,000 miles for the next oil change.



We have no idea how long it takes the OP’s son to drive 5k miles. What if his driving patterns mean that he only drives 5k miles per year, with mostly short-trip local driving?

My suggestion is to do 2 or 3 oil changes at 1 month intervals, in the hope that this will help to rid the engine of the gunk that has accumulated over several years of “extended” oil changes. If the oil looks reasonably clean after 2 or 3 of those one month oil changes, then I think it would be safe to go to longer intervals.

However, we still don’t know whether the OP’s son drives 5k miles in one year, or in six months, or…? At the very least, he needs to change the synthetic oil at least once each year after those 1 month oil changes, but more often is certainly better. Personally, I won’t go more than 5-6 months between oil changes.

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And if that low oil PRESSURE light EVER comes on again tell your son to stop driving it immediately and check the oil level. He should walk to the nearest place that sells oil if it is low. Anything else can result in a destroyed engine.


From this point forward, add this to the engine oil before having the oil filter/changed.

And he may be able to get more miles out of the car.


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You’re right, I suppose I assigned my driving habits to the poster’s. I will hit 5k miles before 6 months.

I’m not sure I’d go changing the oil more frequently than necessary, though (once a month for a period), unless I was doing some sort of flush. I just don’t think it’s really going to make much difference. 1 month old oil isn’t going to remove much more sludge (if any) than 3 month old oil. And I don’t think the sludge is going to come out quickly enough to contaminate the oil really early (again, unless you’re doing a flush).

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You could well be correct.
It is entirely possible that the OP’s son has neglected the maintenance of this engine to the extent that a mechanic will have to open it up and clean it out with his hands and tools–at significant expense. But, it might be worth a few short-duration oil changes to see if the expense of opening up the engine can be avoided.

I would still like to know…
How many miles per year does the OP’s son drive?
Is his driving pattern largely short-trip local driving?
and, most importantly
What was his son’s regimen for oil changes over the past few years?

So he just started a new job and has about a 30 mile drive each way, not much stop and go traffic at all. He was working a temporary job where he had about a 15 mile drive daily, but was working security and basically sat in his car for the majority of each shift, so it was running a lot. He is also a firefighter and has lights in his dash and sometimes drives fast to get to the fire department.
Oil changes, as far as i know he was getting them done with synthetic and close to the recommended schedule. I’m sure he went over a little occasionally, but I’m really not sure. I have always done mine regularly so he was taught to do the same.

Extensive idling is not good for the oil. In a circumstance like that, adhering to mileage intervals could lead to oil changes being done much less often than they should be.

And, being “close” to the recommended schedule probably means going past the recommended interval. Then, when you factor-in a lot of idling, sludge build-up in the engine takes place. With his type of use, changing the oil more often than is specified in the mfr’s maintenance schedule is vital.


My theory is, the synthetic will get some of the sludge out over time. I don’t think ultra short duration oil changes are going to accomplish anything extra. Won’t make the sludge come out any faster, and it’s not going to come out fast enough to sludge up the new oil you’re putting in there. I could be wrong, though.

I think we’re jumping to conclusions on how much sludge is in there anyway. The main thing I took away from the first post was that they allowed the oil level to get low. A little gunk under the oil cap may not necessarily mean the engine is sludged up.

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Agree with the above for sure. 5k miles (or 6 months) would be my max. Maybe less if idling extensively. Honestly, I’d try to avoid extensive idling at all.


The damage has already been done if any. Just do as the others have suggested and hope for the best with changing oil and keeping the level up. First thing to if the light comes on is check the oil level.

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The only experience I ever had like this ended miserably.

The code for the cam sensor was probably caused by the low oil level. W/any luck just keeping the oil and filter fresh will solve that problem. The question at this point is whether there was any internal engine damage done by operating the engine w/too little oil. If there was you’ll soon know; otherwise not much to do but keep an eye on the gauges, checking the dipstick, etc.

The color of the drained oil doesn’t look that much different than when I routinely change it at around 5,000 miles. But its hard to tell for certain just by looking at the photograph.

The fact that the lack of oil pressure light turns off means nothing. It takes very little oil pressure to turn off that light and while the light may go out that does not mean there is enough pressure to safely protect the engine.

Black oil, less than half a gallon of oil in it means trouble ahead and any oil consumption issues are going to get worse.

Not a car I would recommend taking on a road trip and unless he gets in the habit of checking things under the hood every week or so his automotive longevity future is going to be dim.

First, I agree with doing another oil change within a 1000 miles and checking the oil level before the first drive of the day for at least the time till that 1000 mile oil change.

Next, when the car is warmed up, check the oil level with the engine running and then five minutes after shut down. There should be less than a 1 quart difference. The oil level will be lower with the engine running.

If there is more than a one quart difference, that could be due to the drain back holes in the head getting gunked up. That would take a mechanical cleaning. A one quart difference is close to normal, over that indicates a problem but maybe not urgent. Two quarts difference would be more urgent, three immediate.


I really don’t think that is a good idea . We have no idea just how experienced the person is around engines . A loose article of clothing could catch in the fan or serpentine belt on a running engine .

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