I have a 90 maxima w/ a single cam vg30e engine. I know it has high miles 158k but since my last oil change I put almost four quarts of oil because it runs low very quick. I do drive the car in NYC so I know I revve the engine hard but not that bad. The oil absolutely does not leak from anywhere. Is there any oil treatment I could use to help me out.

 

if your burning almost ALL your oil, you have to have a leak somewhere. Man, your engine must be all black and nasty..you should get that flush bill talked about in his oil comparisons. Your valve seals could be leaking oi, which is what this sounds like. Check your spark plugs for fowling, i can amost gurantee that you'll see this.

If i were you, I would have your car inspected and compression tested. A compression test would let you know if your valve seals are bad. It's cheap. I run on RedLine motor oil, which is VERY expensive, I would not like to have to buy a bottle every week, it adds up to be alot. The faster you find the solution, the more money you save.


Good luck.

 

Not necessarily. I am having a similiar problem. I change my own oil and I use Mobil 1 10W30. I get about 1500 miles into a change, and have lost nearly half of my oil. I have no leaks, my car is garage kept, and I don't see evidence of a leak in the engine bay.

 

Having a car garage kept only means you won't get banged up (body and paint). Functionality has nothing to do with a garage. You do not have to see physical evidence in order for there to be a leak. Valve seals are tricky that way. Valve seals can leak very slowly in a way you do not even see smoke at all, but over time you burn alot of oil. Burning more than a quart or even two quarts is pretty unusual, and is a sign of some problem. The easiest way is to check your spark plug for fowling and if it is messed up, perform a compression test.
If you have been using conventional motor oil all the time and switched to synthetic on an high mileage motor, then you risk possibly uncovering leaks. Certainly your driving habits play a role also, but you guys are burning alot of oil.

Check your spark plugs. Do a compression test.

Good luck.

 

Why would a compression test tell you anything about valve seals? A compression test will tell you about the piston rings and the valves themselves, perhaps, but the valve seals are behind the valves, behind the cylinder head ports, and are not part of the combustion chamber.

 

That's a good point I think, since it just sits there and measures accumulated pressure doesn't it?

I think the reference to the garage was only to state he doesn't see pools of oil under his car where he parks everyday... (?)

There are 4 ways that oil can disappear:
1)Leaks out onto the ground from a bad seal somewhere
2)Leaks into the coolant system, which makes it brownish or milky(?)
3)Leaks through the valve seals. You can tell if it's doing this if theres a puff of bluish grey smoke out the tailpipe when you start it up after it's been sitting overnight.
4)Leaks through worn piston rings. You'll see the smoke puff this time when you're coasting downhill, accelerating hard, letting off the accelerator... You might need a buddy following you to see this better or you might not if it's so bad.

 

Yep, no puddles in my garage, and as for #2, no oil in the coolant.

As far as #3 goes, I see a little smoke, but not for very long. Seems normal to me, but maybe not.

 

Also change your PCV valve. it's a $3 part that is often overlooked and can cause oil consumption due to pressure building up inside the engine.. can make the engine push oil around the valve stem seals and piston rings when it otherwise wouldn't.

 

Yeah, I did that, and the little hose too.

 

I seem to be losing oil w/no puddles or obvious smoke. I was getting the oil light intermittently thinking it was a fluke, but the dealer said I was almost out of oil. I'm getting the intermittent light again.

Is fixing this an expensive proposition?

 

Of course if you put 4 quarts in -- and you haven't changed your oil in 6000 miles - that might not be bad...

1 Qt for every 1000 miles ain't bad for a 158k motor...

My dad had a Chevy astro van that he never changed the oil in -- just added as necessary - got 180k on that motor..

Saved a butt load on filters and oil!!!

 

You probably have worn main seals. If the oil is leaking out that fast, that are about the only things left providing all else that others have mentioned in this thread are good.

---WELL, I HAVE NO OIL IN MY DRIVEWAY. IT CAN'T BE A LEAK---
Yes it can. Reason: if either your front, rear, or both main seals are leaking, they will only leak when you have oil pressure. When your car is parked with the engine off, your oil is concentrated in the oil pan and the oil filter. Therefore, you will not see any stains or leaks then. However, when the car is started up and driven, the oil is then under normal operating pressure. This normal oil pressure can push the oil pass worn main seals. However, this will only happen when the car is driven. If you were to put the car on a lift, you would notice a long oil streak staining the car's undercarriage.

---THE ENGINE BAY LOOKS GOOD---
Again, the main seals are toward the bottom of the engine. When you look under the hood, all will appear normal. Get underneath the car.

---HOW CAN YOU TELL IF IT IS THE MAIN SEALS---
Start the car and set the throttle to rev the engine to about 2500 to 3000 RPM. With the engine reving and producing oil pressure, look underneath the car from the front for a while. Your heart will practically jump out of your chest when you see the oil seeping.

---HOW I KNOW?---
This is excatly what happpened to my '91 Sentra GXE, a friend's '93 Maxima GXE, and another friend's '89 Honda Accord LXi.

---IS THERE ANYPLACE ELSE THAT CAN LEAK OIL UNDER PRESSURE?---
Yes, the oil filter bracket. It can leak an enormous amount of oil if the gasket is severly worn.

Also, there is not amount of oil treatment to "seal" a leak of that magnatude. Repair is the only option. In your case, since you have the VG engine, you will want to replace the timing belt if you have the front main seal replaced. If it is the rear seal, goodness help you as you will have to separate the transmission from the engine to get to it. On the Honda Accord that I mentioned earlier, it was leaking from BOTH seals.

Whatever you find, let us know so that we can add it to our mental databases.

$0.02 deposited.

 

maybe you rpiston rings are worn out does it smoke at all???

 

the reason im replacing my engine is because of the front main seal my car would loose about as much oil as your describing i couldnt keep oil in it but it wasnt leeking anywhere i could see but then i noticed one day that there was oil all around the front crank pulley and quess what my front main seal was bad so dont wait to long or just make sure theres always oil in it and dont rely on the oil light it didnt ever come on for me and mine was very low at times

 

A compression test CAN tell you about your valve seals by process of elimination. If your compression is good, and you are still burning oil, then it pretty much HAS to be your valve seals. That's the only other way oil can get into the combustion chamber.

 

There is a section in Chilton's discussing high oil consumption. It starts at the bottom of Figure One and continues into Figure Two in this link:

http://www.cybrrpartspro.com/Chilton...61CH03_TC.HTML

Unfortunately, the print is very small and difficult to read. I tried downloading the pages and then zooming in using Windows XP picture viewer but that was only slightly better. Perhaps printing out the two figures would give you more readable copy. Hope this helps. Good luck.

 

In general, if there is pressure buildup due to a clogged PCV valve, it is wise to check the air intake hoses (sometimes called a blowby hose) to the valve cover. When the PCV is clogged, all blowby gases will flow out the intake hoses. These usually contain a flame arrestor which sometimes looks like a large pipe cleaner. When this gets clogged the crankcase will pressurize. It is wise to check that this hose is clear whenever changing the PCV.

The service manual schematic shows two intake hoses on the VG engine.