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Car Forum / Nissan / Nissan Cars / March 2006Changed Oil, Now Oil Light on at Idle. 96 Sentra.
Hi, I just changed the oil and filter on my gf's 96 Nissan Sentra (170,000 miles) and now the oil light comes on after the engine is warmed up, when the car is in Drive, and stopped, such as at red lights. After 300 miles of this, I put a different brand of filter on, but the problem remained. After 200 miles with the different filter, I changed the oil again (not filter), and the problem remained. Maybe the crank bearings are just too worn, causing the low oil pressure , and it's just a coincidence it happened right after the oil change, but I'm hoping the cause is sludge. I kept the original oil filter, and looked inside. Inside, I could see a layer of dark gray slime (sludge?) about the consistency of the grease you pump into a ball joint, laid down on the bottom of the filter ! The filter is mounted horizontally, so the slime was going from front to back, about a 1/8 to ¼ inch deep ! This sludge was in the post-filtration portion of the filter, the long channel down the center. It wasn't high enough to block oil flow back into the feed tube though. The oil light was not coming on before the oil change, even with all this sludge. But now it is. I've been changing the oil and filter every 5K to 6K on her car, but I had to leave the old oil filter on the previous time, since it refused to come off and I decided to deal with it later, so I just changed the oil and not the filter back then, so this sludged up filter had about 10K to 12K on it when I removed it. I would think other parts of the engine have sludge too, like the bottom of the oil pan where the oil pickup is. By looking into the oil filler hole, I can't see any sludge on the head. Looks very clean. There's nowhere for the oil to pool in there, at least from what I can see. Maybe the sludge is only forming where the oil can pool. I read somewhere that sludge around the oil pickup screen can cause the symptoms her car has. When I drained the oil, no sludge oozed out, just normal oil. And I changed the oil hot. Dropping the oil pan looks like a major ordeal on this car: exhaust pipe and support beam in the way. I had an idea for desludging any possible sludge on the pickup. I could heat up a quart of transmission fluid , drain the crankcase, put the drain plug back in, then pour the hot ATF into the engine, let it settle down around the pickup screen, and let it soak for a day or two, then drain it out, examine what's in it, then pour a quart of fresh oil in to flush out whatever else is there. Sound OK ? Any other suggestions welcome ! Thanks Correction ! : the sludge is JET BLACK, not gray. It looked gray when I shone a light into the filter, but when I scooped some out and wiped it on a white sheet of paper, it is clearly BLACK . Sorry for the misinformation! > Hi, > [quoted text clipped - 55 lines] > > Thanks I'd put a real pressure gauge or just change the sender for the light before you do anything else. It's very common for senders to fail. Have the oil pressure properly checked, in case it is the sender that is bad. The pressure sensors sometimes go defective. In the other case, if the oil was not changed frequent enough, the bearings, or possibly the oil pump may have worn down faster. The thickness of the sludge that is now cleaned out, may have been keeping the pressure up to an acceptable amount. If the pressure is down from wear, you can try a thicker oil, or use an additive for low oil pressure. If the motor is at that point, you can be sure that its days or months are numbered. If he rest of the car is in very good condition, including the transmission, rear end, and suspension, it may be a good idea to have the motor rebuilt. But, before investing this type of money, you want to be sure that the cost is worth it. -- I found that with most cars, if they are run on regular oil for the first 10,000 miles or so, and then put on to synthetic oil, the engines last a long time unless abused, or something by a coincidence goes defective. A key factor to have an engine last a very long time, is to change the oil and filter often.  SignatureJerry G. Hi, I just changed the oil and filter on my gf's 96 Nissan Sentra (170,000 miles) and now the oil light comes on after the engine is warmed up, when the car is in Drive, and stopped, such as at red lights. After 300 miles of this, I put a different brand of filter on, but the problem remained. After 200 miles with the different filter, I changed the oil again (not filter), and the problem remained. Maybe the crank bearings are just too worn, causing the low oil pressure , and it's just a coincidence it happened right after the oil change, but I'm hoping the cause is sludge. I kept the original oil filter, and looked inside. Inside, I could see a layer of dark gray slime (sludge?) about the consistency of the grease you pump into a ball joint, laid down on the bottom of the filter ! The filter is mounted horizontally, so the slime was going from front to back, about a 1/8 to ¼ inch deep ! This sludge was in the post-filtration portion of the filter, the long channel down the center. It wasn't high enough to block oil flow back into the feed tube though. The oil light was not coming on before the oil change, even with all this sludge. But now it is. I've been changing the oil and filter every 5K to 6K on her car, but I had to leave the old oil filter on the previous time, since it refused to come off and I decided to deal with it later, so I just changed the oil and not the filter back then, so this sludged up filter had about 10K to 12K on it when I removed it. I would think other parts of the engine have sludge too, like the bottom of the oil pan where the oil pickup is. By looking into the oil filler hole, I can't see any sludge on the head. Looks very clean. There's nowhere for the oil to pool in there, at least from what I can see. Maybe the sludge is only forming where the oil can pool. I read somewhere that sludge around the oil pickup screen can cause the symptoms her car has. When I drained the oil, no sludge oozed out, just normal oil. And I changed the oil hot. Dropping the oil pan looks like a major ordeal on this car: exhaust pipe and support beam in the way. I had an idea for desludging any possible sludge on the pickup. I could heat up a quart of transmission fluid , drain the crankcase, put the drain plug back in, then pour the hot ATF into the engine, let it settle down around the pickup screen, and let it soak for a day or two, then drain it out, examine what's in it, then pour a quart of fresh oil in to flush out whatever else is there. Sound OK ? Any other suggestions welcome ! Thanks > Hi, > [quoted text clipped - 31 lines] > I would think other parts of the engine have sludge too, like the > bottom of the oil pan where the oil pickup is. It would. > Looks very clean. Then sludge isn't the problem as it's always worse on the head. > There's nowhere for the oil to pool in there, at least from what I > can see. Maybe the sludge is only forming where the oil can pool. I'd be hoping the sensor is bad which is likely the problem. > I read somewhere that sludge around the oil pickup screen can cause the > > symptoms her car has. Nope, it causes problems an ANY RPM not just at low idle. > When I drained the oil, no sludge oozed out, > just normal oil. And I changed the oil hot. Sludge -won't- drain out. > Dropping the oil pan looks like a major ordeal on this car: exhaust > pipe and support beam in the way. I had an idea for desludging any [quoted text clipped - 6 lines] > in it, then pour a quart of fresh oil in to flush out whatever else is > there. Sound OK ? How about trying a new oil sending unit or better yet actually checking the oil pressure with a gauge before you condenm the engine. SignatureSteve http://www.atlantaracing.com |
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