Dear heavenly forum frequenters—bless me with thy knowledge.

I have an 85 Fiero with a 2.8 V6 that likes to burn oil. As mentioned in the title of this thread, it goes through one quart every 300 miles or so.

First, I tested the compression of each cylinder. To make a long story short: the lowest reading was 135psi, and the highest was around 142. Not super high (the engine wasn’t very warm at the time), but it told me that all of the cylinders are in about equal shape.

I proceeded to replace the valve stem seals—more accurately, it was like I added valve stems seals. What remained of the old o-ring seals looked and felt like shattered plastic. Anyway, that went well enough. It didn’t do a damned thing as far as slowing the oil consumption, though.

There are no oil leaks on the outside of the engine. Not a single one. The installation of a new lower intake manifold gasket set stopped what little oil was leaking, but that was over a year ago.

I used to use 5W-30 Castrol GTX, but I switched to 5W-30 Havoline oil about five months ago. It is easier on the wallet. The oil filter gets changed every 3-4000 miles. The oil is changed…well, the engine only holds 4.5 quarts, so you can do the math.

The PCV valve is new, and there is no sign of oil getting sucked out that way.

My last thought (not that I’m about to give up on the car—just that I’m about to stop thinking) is of the EGR. Just a few days ago, when I was on a two-hour highway trip, the “check engine” light came on. It was a code 32. The EGR valve is good—I pulled five inches of vacuum on the EGR valve while the car was running, and the engine responded as it should. As all of the vacuum lines have been replaced with Rodney Dickman’s steel set, I am thinking that the EGR solenoid is not doing its job. While that is all well and good, my question to ya’ll is this: could a malfunctioning EGR solenoid cause the engine to burn such an incredibly high volume of oil?

Im fairly certain there is no way the EGR could have any effect on oil consumption at all.

I know you said you're not leaking, but I cant think of anything else to check short of tearing down the engine, so check the disributor oring, the plate between the engine and tranny to see if the rear main or cam cover is leaking, and the valve covers, especialy the rear as the oil could leak onto the exauast and smoke off. a quart every 300 miles is a hell of a lot of oil, theres got to be signs if its going out, and should be smoke if its going through.

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quote Originally posted by 86GT3.4DOHC: Im fairly certain there is no way the EGR could have any effect on oil consumption at all. I know you said you're not leaking, but I cant think of anything else to check short of tearing down the engine, so check the disributor oring, the plate between the engine and tranny to see if the rear main or cam cover is leaking, and the valve covers, especialy the rear as the oil could leak onto the exauast and smoke off. a quart every 300 miles is a hell of a lot of oil, theres got to be signs if its going out, and should be smoke if its going through.

The o-ring on the distributor is new. The rear main seal is new. The valve cover gaskets are new. The cam cover gasket/seal is not new. However, there is no oil leaking from any of these areas. I would think you are right: an engine that is truly burning 1 quart every 300 miles should smoke like a chimney. However, outside of initial start-up, there is absolutely no smoke. The exhuast tips are nice and oily, though.

There is a catch-phrase that people are using is that something is "sucking" the oil out of my engine--EGR, PCV, you name it. It makes no sense to me, but I have tried just about everything that would seem to make sense.

If it was leaking I would think that there would be oil drips under the car. It always parks in the same place, and there are no drips. I need to learn a new language--I have run out of original ways to swear about this.

[This message has been edited by go_home_red (edited 01-30-2006).]

Edit, it not buring the oil, the exhaust pipe tips are oily though. This is strange.

88Ironduke

[This message has been edited by 88Ironduke (edited 01-30-2006).]

The last engine that I had that used that much oil was a ring problem and it was burning it. With oily exhaust, you found the trail. Sounds like there really isn't much of an alternative to the burning other than an engine change/overhaul, or start by trying a heavier oil such as ( yuk ) Quaker State high mileage oil. That or some STP goop and see if that slows it down a bit.

Good luck.

Mark

[This message has been edited by Firefox (edited 01-30-2006).]

Regarding the need for an engine overhaul, this is the hardest part to take--the engine runs perfectly. It doesn't knock, it doesn't run rough at all. It is the smoothest engine. On top of this, it was just this past week that I got back from a huge road trip in the car. Omaha (Papillion), NE to Houston (Dickinson), TX to San Antonio (Seguin), TX to Chandler, AZ and back to Omaha, NE. That's a 3800 mile trip, and aside from burning a quart just about every tank, the car was incredible.

Tomorrow I am going to (very carefully) do a couple of kerosene flushes. Sure, it might make things worse, but how much worse could it get?

The catalytic converter does a good job of getting rid of unburned hydrocarbons - this includes oil vapor. Your engine could be burning a lot of oil and you may not see any blue smoke, or only see it infrequently.

A quart every 300 miles is either a obvious leak or a worn-out engine. Look at the bottom of the trunk; if you're leaking it the bottom of the trunk will be oily. Most likely, though - it's time for an engine rebuild.

Switch to 15-40 oil. If that does not do it go to 20-50. Use a half quart of tranny fluid in the mix too. It is likely that you have stuck oil control rings, the detergant in the tranny fluid will help with that.

Another thing to try, just to be positive, is to pull the PCV up out of the valve cover and drive it that way for a few hundred miles.

quote Originally posted by go_home_red: The installation of a new lower intake manifold gasket set stopped what little oil was leaking, but that was over a year ago.

An intake manifold gasket that was installed badly could leak oil into one or more intake passages.

The good compression readings could be an indication that the oil control rings are stuck or worn out. Try to take another compression reading after the car has sat overnight, when the cylinders are dry. When there is a lot of oil on the cylinder walls, it can seal worn-out compression rings and yield a normal compression reading.

When did the problem start? Did it start using oil abruptly, or did the high oil consumption develop slowly? How many miles are on the engine? How many years since new or its last overhaul? The answers will help to zero in on the problem.

The engine has just over 150,000 miles on it.

How long has it had an oil fetish? I bought the car in July 2003 and worked on it until December 2004, which is when it became my daily driver. It burned a little oil then, but it was only after replacing the vacuum lines (a few of the originals were broken) that I really started losing oil. However, that doesn't make much sense to me--vacuum lines shouldn't effect oil consumption. It has to be something else.

As for this "pull the PCV" business--I'll try it, but if that's how the oil is getting out, wouldn't that just make an oily mess?

No that maybe a indicator of what it is not.....

If it is burning the oil at a constant rate, the plugs maybe able to keep themselves clean. I would think that would eliminate the chance that it was leaking intake gaskets since one would think one or two cyl. would get more oil than others.

It maybe back to the oil rings are all stuck and it is burning the oil on all cyl. at a nice(or not nice ) steady rate.

If you watched the exhaust in another car's headlights at night do you see a light amount on smoke. Makes it easier to see smoke that you really don't see during the day....

If the car sat for some time before you bought it the ring might have all got stuck and never came free.

[This message has been edited by Dodgerunner (edited 01-31-2006).]

quote Originally posted by go_home_red: As for this "pull the PCV" business--I'll try it, but if that's how the oil is getting out, wouldn't that just make an oily mess?

It is really not getting out there, but getting sucked in. If the PCV is not in the engine it does not have the ability to draw it into the intake. Also look into the hole from the PCV and make sure that the baffle is there.

Would a PCV that was stuck open also draw all the time?
But that would affect the idle and running also...

An old mechanics trick for getting oil rings, or rings in general, unstuck is to pull all the plugs and squirt each cylinder full of Marvels Mystery Oil, then let it sit overnight. Put the plugs back in, fire it up the next day and run it awhile. If it works, you've bought yourself a little time, but with the mileage you describe, its probably time for an overhaul, or new shortblock. As someone mentioned earlier, try running a heavier weight oil, 10w40/20w50 mix. Should slow the consumption down a little.
Good luck, Todd

Here is a old timers trick. Get the car up to about 70 mph and then let off the accelerator and let it coast down to about 20 mph and then floor board it and if you see big puffs of smoke coming from the exhaust then your rings are bad.
Don