Why is my 98 Nissan Sentra burning oil?

Question

I am having problems with my 98 Nissan Sentra burning oil. I have taken the car to a mechanic and he said he found no leaks (I didn't really want to spend the extra money for him to take apart the car to find the problem). I just started a new job and there is one intersection on my way to work where the car always burns a lot of oil. It only does it in 2nd and 3rd gear (if I am going through the intersection at faster speeds nothing happens). I will go over a small bump in the intersection and feel the car not want to accelerate and sure enough there is a big cloud of blue smoke behind me. Now the car burns a quart of oil each week (I drive a little over 300 miles a week comuting to work). I've also noticed that the car seems to burn a lot of oil when I am driving in the city in stop and go traffic. With the exception of a few intersections, the car doesn't seem to be burning oil (there is no blue smoke most of the time). Does anyone have any idea as to what the problem could be?

Thanks for all the answers. I ordered a compression tester, but it sounds like I'm going to be in the market for a new car soon. I understand that the car may be burning oil all of the time and I just can't see it, but why would the car burn so much more just at certain intersections?

Answer 1

If your losing oil, it's got to be going somewhere. If you see the big cloud of blue smoke it's definitely being burned off. There are three ways for oil to get into the combustion chamber.

1. Worn Rings. Oil is bouncing up into the cylinders and getting pass the piston rings. This sounds like the most likely scenaio.

2. Worn Valve seals. Oil is dripping down the valve seals, past the valves and into the combustion chamber. Also a possiblitiy.

3. Bad head gasket and oil is leaking into the combustion chamber.

All three require some major engine work. In the short term it may be cheaper to just check the oil every other day and fill the oil to the proper level you need. As long as the engine has oil, it will continue to run and not seize, but eventually the burning oil will foul your plugs, which may be what you're experiencing with it not wanting to accelerate.

If you don't have the money to fix the car, your short term solution may be just to check the oil frequently and change out/take out your spark plugs and clean them. (depending on how quickly they get fouled up). This will at least keep your on the road.

If your interested in determining if it's the rings or the valve seals, a compression test (both dry and wet) will help you determine which of the two is more likely. You can do a compression test yourself. A good compression tester typically costs less than $75 and can be purchased at any parts store.

Answer 2

get a compression check,, you can buy a compression device for about 30 bucks and it is easy,, warm up your car, take out all spark plugs,, install the compression checker into the spark plug hole and turn the engine over for 4 revolutions and then check the readings,, do this for all the spark plug holes the readings should be pretty close to each other,, if you have a low reading in one cylinder then you either have a bad ring or a bad valve,, to find out put about a teaspoon of oil in that spark plug hole that was low and test again,, if the reading goes up then its a bad piston ring,, if it does not then its a bad valve good luck,, a shop can do that for you as well

Answer 3

Sure, either your valves or rings are leaking. 300 miles a quart seems to be a lot.

Do you know your single car is causing more pollution than about 10,000 other cars that are running correctly?

Please get it repaired or replaced. Just because you can't see the blue smoke coming out your tailpipe doesn't mean you're not burning oil. I absolutely hate following cars like yours in traffic.

Do the world a favor and replace the car. A '98 Sentra isn't worth the cost to fix this problem.

Answer 4

i own a repair shop,,and it sounds like that it has either a head problem,,or has a broken,,or weak ring in it,,this will cause it to do that,,if it has ever been real hot before,,it could have weakened the piston rings in it,,this will cause it to do that,,also it will make it loose power,,and the smoke will probably get worse on it ,,as time goes on,,have another mechanic look at it,,and get his opinion on it,,it may need to be rebuilt,,or you may want to find a good low mileage motor,,and swap them out,,rebuilding them can be expensive to do,i hope this help,s..good luck with it.