I have been wondering where a quart of oil goes every 1000 to 1200 miles of driving my 71 cutlass with a 455. Tonight I had it out and noticed the faint smell of oil when I took my foot off the gas after bringing it up to 80. I haven't noticed this before but the windows are usually down during warmer weather. Since I replaced the leaking power steering pump, I haven't seen any oil/fluid on the floor, so I'm pretty sure it's burning the lost oil although I have never seen any blue smoke out the tailpipe. The car runs great, so I just keep it topped off, but I would be interested to know what the gurus here think might be the cause and if there is anything to worry about.

 

What oil you using? Try using a premium high viscosity oil.

 

Usually Valvoline 20-50 in the summer and 10-40 in the winter with Risoline zinc additive.

 

That's good oil and good additive. My suggestion was more of a long shot, yet there are instances low viscosity cheap oil gets burned up much faster than a premium high viscosity oil.

 

I have had many classic V8 motors. In my experience, going through a quart or two of oil between changes is the norm not exception. Almost three quarts is more than I am used to.

 

I don't know the answer to your oil loss. I recognize "some" history of your posts, but not all. As a suggestion, which would be where I'd head first if it were my engine, I'd perform both a dry and a wet compression test on the eight cylinders. I think, in general, either worn/stuck piston rings or worn valve seals first come to mind. Performing a dry & a wet compression test is inexpensive & the numbers can provide decent insight on the possibility of bad rings &/or worn/stuck valve seals. Just a suggestion and easy to perform.

 

Right. Well, a quart of oil between changes is relative to the number of miles between changes. A quart every oil change might be normal if the oil change is ~3K miles; but, every engine is different. On my 350 w/ good valve seals and a compression of 135psi/140psi on every cylinder I experience absolutely no oil lost between 3K mile oil changes. Perform a compression test & gain some insight, if you want to go further perform a leak down test.

 

Just a long shot but the PCV system is often overlooked as a cause of oil consumption. Maybe replace the valve & clean the breathers or replace. I've dissected good looking breathers and found them corroded inside with rust.

 

Generally speaking, a puff of blue oil smoke at start up can be attributed to worn valve guide seals, while smoke upon acceleration is a sign of worn rings. Norm is right on the money suggesting a dry/wet compression test.

 

This is interesting. I didn't know oil had a smell, at least that you could notice as obvious the way you can with gasoline. I've changed the oil on my cars about 100 million times over my life, and I've never noticed any particular odor from the oil in the collection pan.

My guess is that you're either imagining the smell because the power of suggestion is a real thing, or you're smelling some other fluid.

How many miles on the engine? As engines wear, they consume more oil.

If it were me, putting in a quart of oil every thousand miles is nothing to worry about. I wouldn't tear the engine apart trying to fix it or pull my hair out worrying about it. If it needs oil every time you fill the tank, then I'd worry.

 

Oil most certainly has a smell. Its a lot stronger when its hot though.

 

I'd suggest refreshing the PCV system and making sure that is functioning properly first. It's a cheap hedge to start with. If that doesn't cure it, it is time to do the compression and leakdown tests.

 

My guess would be valve stem seals; perform a compression check and leak down test. Let us know what you find.

 

How do the spark plugs and tail pipes "read?"

 

The was a year ago. Oil consumption was about the same.

 

That looks OK. How many miles on the engine?

 

About 35k

 

The car runs really well. Not a race car but very torquey with very crisp throttle response.

 

7 other plugs look like the one above?
1qt every 1-1.2K isnt horrible. Its elevated but not to the point of concern.
Verify the PCV isnt pulling it in. Verify the correct valve is installed etc.
Run it with the PCV removed still connected to the hose end. Pull the tube off the other valve cover. Run the engine and observe the amount of blow by. If its not excessive your are ok.

 

The other plugs look the same except the passenger rear which I don't have the tools to access. This also makes it tough to do a compression test since I believe all the plugs need to be removed to test. I will check for blowby as described above. I replaced the PCV recently. I will check for oil in the line to the carb. Not sure if this would indicate a bad valve, since I would assume there would be a little oil residue in the line over time. Correct me if I'm wrong.

 

The back passenger side is always somewhat of a challenge. It's preferable you perform the compression &/or leak-down on all eight cylinders; yet, seven cylinders would probably suffice as it represents 88% of your cylinder compression.

 

Make sure you do a compression test on all the cylinders. If you need a 3" extension or wobble extension then buy one.

Also, make sure you have another car running with jumper cables connected when you crank over your 72 and do the compression test. Without another car running jumper cables you'll quickly drain the battery and get a bad compression reading.
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Interesting, Jesse. Good suggestion. I've never had that issue but it makes good sense. Maybe instead keep a proper battery charger attached might work, as well?

 

There was no smoke whatsoever coming out of the PCV hole on the valve cover when I removed both tube with the PCV still in the one tube.

 

That would work just as well if it's available. I have a 2/10 Amp charger that I don't think would keep up with cranking the 455 in my 71 for very long. Last time I did a compression test I did it dry then tried to do it wet. The battery didn't last through the wet compression test so MAW keep the battery healthy if you can.

 

One thing I noticed was oil on the PCV valve. No smoke, but oil. Is that normal or is something like the valve cover baffling not working. Regarding compression, a test would be good, but when I used a vacuum meter to set my idle mixture, I also did all the diagnostics I found online for which the meter can be used. I don't remember the indicator now and would need to refer to the website, but the meter test indicated there wasn't a compression issue.

 

Baffles inside the valve covers shouldn't be an issue w/ regards to burning/losing oil. I'm not following you regarding use of a vacuum gauge (meter). Yes, you can use a vacuum gauge on your vacuum lines to check vacuum, establish/adjust your carburetor A/F mixture screws (and set idle). Most vacuum gauges are dedicated to reading vacuum and it is measured in inches of mercury (Hg). If it's a dual function gauge, you may have used a dual function gauge which can read both vacuum & fuel pump pressure. However, fuel pump pressure readings are almost always below 30PSI when included on a dual function vacuum/fuel pressure gauge. A compression test gauge needs to be able to test up ~190PSI. Generally, a compression test gauge is a dedicated gauge. Therefore, I'm unclear how the meter you used indicated there wasn't a compression issue.

 

I perform a dry & wet test on one/each cylinder then move to the next cylinder & perform same (dry/wet), etc. To each their own, right? You still bring up a good point regarding the battery.

 

I encourage you to research what a vacuum gauge can be used for as an initial diagnostic tool. You won't get specific compression numbers using one, but you can use it as an initial diagnostic tool to determine if there is a problem with compression, as well as other things, before further more specific testing.

 

I've used a vacuum gauge for ~50 years. If you don't want to perform a compression test...your call.

 

Guys, if you have all the plugs out doing a compression test, it don't take a lot to spin the engine over. I have never had a problem with all the plugs out. Maybe I just had a good battery.

 

Glenn - Fully agree & that's how I go about doing the test. I remove them all then begin the test, one cylinder dry>wet, then move onto the next. You bring up a valid consideration none-the-less I do remove all the plugs before I begin. Good call.

 

A tip on pulling that #8 plug on the passenger side. I have had two 72 Cutlasses with 350's. I have a spark plug socket for a 3/8 drive ratchet. But, on the top end of the socket, it has a hex head for a 3/4 inch box end wrench. The image below is a little large. rench. This is the only way I have ever got that plug out.

 

That's the diagram I saw. There is a good write up with it. The motor had 150 psi within 10 percent when installed. Nothing has changed with the way it runs or the amount of oil it uses since then. Actually it runs better since I have made adjustments to the timing and carb. I would be interested to know if oil on the PCV is normal. It would seem to me when the valve opens it would pull oil into it if oil is coming into contact with it.

 

Sorry somehow I posted the image twice. But you get the picture.

 

Exactly same as me. I think I may have the longer extended version. But, you're correct, slide the socket onto the plug then use a box-end wrench. It's actually more difficult to get the plug wire on/off.

 

Thanks for the image. With the 455, I can't even get my hand in there to pull the wire. When I had the head gaskets replaced, I asked them to leave the unreachable fasteners off so I could remove the inboard site of the box to replace that plug. The AC is disconnected.

 

I'm only trying to provide some thoughts on direction/diagnostics. I personally think 3 quarts of oil between 3K mile oil changes is excessive. If it isn't dripping/leaking oil (as you stated) I don't know where that oil is going and that's why I suggested a compression test thinking there exists the possibility oil is escaping into the exhaust - rings &/or valve guides. If you know it's 150psi +/- 10% then move on. We can't determine how people drive their cars, how much work was done, who did the work, what rings were used, blah, blah, blah. Hey, I've had buddies do a full set of rings all the way around and crack/break one or two w/in months - have to admit, they don't hold back on their driving style.

 

I am sure I had to do the same thing on the 455 in my Hurst Olds. Getting the plug wire off can be a real PIA. When age starts catching up with you and you have arthritis in your hands it gets a little more challenging.

 

Thanks for the info. I agree, 2 to 3 quarts is a bit much. Wouldn't there be some blowby if a ring was the issue? I'm wondering it it might be a valve stem seals. I don't think that would cause compression issues since the valves would still seat properly.