So I have a 2003 Nissan Sentra which was given to me by my family and it’s main issue is how much oil it is burning constantly. I find the car to be a lot more safer and reliable than my previous vehicle a 98’ ford taurus. I have my 1 year old son with me daily so his safety is my #1 concern especially when we are in the car so whatever I must do to fix this issue, I am ready though I am hoping to not have to replace the engine. The car is currently at 176,653 miles as of right now. I have done a lot of research on this issue in these past months and this is what i’lve come up with. I have seen a lot of blogs regarding similar issues that their nissan sentra was burning massive amounts of oil due to the manufacturer’s precat. It has been said to relieve the vehicle from its oil burning issue to change the precat to a header so one of my questions is would you find that to be the most reasonable answer, to change the precat to a header?? I was told the precat in my car had been changed previously so I inspected the car myself due to finding the mechanic had replaced the precat with another precat thus making no change to the issue at hand. I am getting really tired of feeding my engine oil when it just guzzles it down in a day or two. Here are some questions i have:
Would changing the precat to a header be the most reasonable solution to ridding this oil burning problem??
(if thats the case this would really relieve me over the stress i endure from this car)
I currently use SAE 10W 40 High Mileage engine oil; the owner manual says to use A) SAE 5W-30 viscosity oil for all temperatures & B) SAE 10W-30 or SAE 10W-40 if the ambient temperature is above 0*F so after using choice B, would changing now to SAE 5W-30 be a good idea???
Would it be a good idea to use an engine cleaner or some sort of cleaner to rid the excess oil from the engine?
Any comments or responses would be much appreciated!
Thanks,
Joseph
I would doubt that the precat is causing your oil consumption. 176,653 miles on the engine probably has a lot more to do with it. Since you are using a thicker oil and still burning oil - that is more evidence that you have a worn out engine. Not sure where the ‘excess oil’ might be in the engine, you are burning everything you are putting in the crankcase. Take the car to a local mechanic and have the compression checked on each cylinder. It will probably be low, meaning the rings are shot.
I would replace the PCV as @missileman stated. More than likely rings, but the PCV can cause excessive oil consumption. A leak down test would confirm rings or valves.
The OP can count this as one more person who doubts that the pre-cat is the source of the problem.
Excessive oil burning is much more likely to be due to…
badly-worn piston rings…
coked-up piston rings…
a gunked-up PCV system.
All of these situations would most likely be the result of a lot of odometer mileage, coupled with inadequate maintenance over the span of many years.
Just in case the OP does decide to get rid of the pre-cat, he/she should be aware that no legitimate mechanic is likely to do this, as Federal law prohibits the removal or deactivation of any anti-pollution devices with which the car was original equipped.
The only ways I could envision an engine using a quart every 140 miles is if the oil rings are gumped up with sludge or if there’s a broken ring. Compression and leakdown tests don’t do a reliable job diagnosing this because the compression rings can still be good even though the oil rings are gumped up.
If it were mine, I’d try an oil additive from the parts store designed to free up sludge. Maybe I’d try twice even. The only other fix I know involves disassembling the engine, and I don’t think you want to do that.
Out of curiosity, how’s the maintenance been? Have the oil changes been done on schedule? Has the oil level been checked regularly and replenished when it’s low?
There is a good reason this car was GIVEN to you! I agree that the engine is probably beyond economic repair. I would get a good used engine if the rest of the car is OK. The high oil consumption is probably the result of less than perfect care and maintenance.
The issue with the precat affects 2005 Nissan Sentra’s and Altima’s with the 2.5 engine. If your Sentra is an SER or Spec V, you have that engine. If its a GLE or GLX or similar model, you don’t have that problem.
The Precat can be the root cause of the oil burning, but the damage it does is to the rings, so replacing the Precat after the engine starts burning oil is like closing the barn door after the horses got out.
The first question I would have to ask is are you sure the oil is burning and not just leaking? If you had a leaking oil pressure sending unit, it would only leak when the engine is running, and most of the time the engine is running, you are moving, so you won’t likely notice oil under the vehicle when you park. Eventually you would see some oil under the regular parking space but it won’t seem like its enough to account for all the oil loss.
If you have an oil leak, chances are it will be cheap to fix. Most common are oil pressure sending units and valve cover gaskets. I poorly fitting oil filter or loose drain bolt could also cause a loss of oil as well. Often the rear main seal is blamed but in my experience, it does not leak nearly as often as it is blamed for. Same for pan gaskets.
If you are getting clouds of smoke, especially when slowing down, then you are burning the oil and that will not be cheap to fix.
VOLUNTARY RECALL CAMPAIGN
ALTIMA AND SENTRA QR25DE ENGINE EXHAUST PIPE
HANGER PIN AND PRE-CATALYST
This bulletin has been amended. This version instructs NTB06-051a be used to reprogram the ECM on 2003 and 2004 Applied Vehicles. Please discard all previous versions of this bulletin.
i have read a lot about people that are having problems with Nissan motors. mostly the 2000 through 2009 2.5L and other motors. the problem with the oil consumption is due to the exhaust valve seal going bad. if you look at the head design around the valve springs they tend to accumulate more oil than other designs. when the valve seals age the oil is pushed down the stem and goes out the exhaust stream. I have had 2 nissans with 2.5L engines and there all the same. when you investigate all other sorces of oil that could make it into the intake there are no signs of oil going through the intake stream or in the combustion chamber. the only signs of oil are in the exhaust stream. and yes this would lead to causing the precat to go bad I’m sure but the root cause of the oil loss is due to bad valve seals. if your plugs don’t show oil build up witch I’m sure they would if you go through 2 quarts of oil every week or so then your rings are fine. the galley around the valves hold oil and when the cam pushes the valve open its like and oil injector. I hope this helps people because theres a lot of inexperienced people making conclusions on just internet info and not having enough experience with engines.
The horse is long gone but I’d wager the problem was a high miles engine that has been driven hard with a shaky oil change regimen. More than likely the problem is in the piston rings.
And yes, I have plenty of engine experience. And then some.
Generally, what is causing the excessive oil consumption in this old Nissan is the same thing(s) that generally cause oil consumption in generally all cars.
Apply your general car knowledge and it will lead you right to the culprit. There is nothing especially unique about an ICE Nissan. CSA
Being babied and perfectly maintained doesn’t mean anything. Many engines are worn our prematurely (or even scrapped out…) long before 94k miles.
Low miles and age combined with a sparse oil change regimen can lead to oil burning due to the oil control rings seizing in the pistons.
So do you have maintenance records for this car? If not, then you have no idea if it was perfectly maintained or not.
Perfectly maintained and excellent condition are 2 phrases that are quite often thrown around erroneously.
That is bad news. On a Nissan the catalytic converters are so close to the cylinder head that when a converter fails debris can be drawn into the cylinders and cause damage resulting in oil consumption.
Inspect the cylinder walls for damage with a borescope and do not operate the engine with a failing catalytic converter.
16 years old, averaging only 6,000 miles/year would scare me a bit…
It’s the low miles that could have taken a toll. Vehicles driven infrequently or frequently making short trips (not always running at full operating temperatures for an adequate duration) develop problems with moisture/water/sludge in the engine and its lubrication system. CSA
