My brother in law has a 95 Civic LX D15 and he's been noticing that it's using a lot of oil. It's used around a quart of oil in the passed two weeks, but he couldn't figure out why. I checked into it last night. The car runs perfect, no problems, misfiring or anything. It doesn't appear to be leaking the oil externally either. I pulled the plugs to see if it might be burning the oil but it's not, all the plugs are the normal brownish-tan color on the tips. We were told by the place where he got the car that they put a new headgasket in it because it was leaking, so I was wondering if they possibly installed it wrong. I did a compression check and came up with 150, 150, 150, 170. This is still within the specifications listed in the Hayne's manual, so that seemed fine. I started wondering if it was the lower spark plug tubes. The 3rd cylinder spark plug had oil all over the threads and the nut portion, but the electrode was perfectly fine. I'm starting to think the oil is leaking into the cooling system. What do you guys think?

 

How about the piston rings?

 

Blue smoke from the exhaust?

 

Have you noticed any milky discoloration to the engine oil? Are you counting the cylinders from right to left?

[intake mani]
(4 - 3 - 2 - 1)
[radiator]

I did a leakdown on my 94 LX D15B7 last night and the #2 is completely shot. 94%. New engine! There was oil on the plug, which is only a few days old. I was also using quite a bit of oil, roughly 1qt per week, but there was no smoking. Granted, I had a couple other leaks like around the distributor and the timing belt wheels, but the tech I was talking with while we were doing the test said hondas are really good about not smoking, so there's a good change oil may be getting through and burning but it won't necessarily show up. If you can get a leakdown done, it's well worth it.

 

From what I can tell from the compression test the rings are good. Like I said, the compression test results were 150 150 150 170. The standard is 180 ish and the minimum is 130 ish and the maxiumum variation between cylinders is 30 ish PSI, all taken from the Hayne's manual. So from what I can tell they're still well within specification. What I am going to do though is squirt a few drops of oil down each cylinder and re-compression test it to see if the numbers increase quite a bit. If they do, I know the rings are blown. There is no smoke at all coming from the exhaust. I would know what burning oil looks like because my blown up Cavalier smoked pretty bad and a friend of mine had an Integra that burned lots of oil and the blue smoke was really apparent.

I haven't noticed any discoloration to the oil. There's been none of the milky white substance to indicate coolant or water in the oil. Also, there's no sweet smell to the oil indicating coolant either. This was one of the first things I checked. The thing is though that it smelled pretty strongly of gas, indicating oil dilution. That makes me wonder if the PCV valve is plugged and not allowing the crankcase gases to circulate and thinning out the oil, causing it to burn the oil quicker.

None of the electrodes were blackened indicating burning oil in the combustion chamber. All of them were the normal tan/brownish color. I'd imagine if it's using a quart of oil every 2 weeks I should be seeing some deposits on the plugs. Only one of the plugs was covered in oil, the rest were pretty clean. I cleaned off all the spark plugs and filled the oil up to the proper level and had my brother in law drive the car a few days so then I can check back and try and figure out where the oil is going. Like I said, I think it's leaking back into the cooling system since the overflow was pretty [freak]in' gunky with what looked like oil deposits. This wouldn't surprise me because the place he bought it from said they had changed the headgasket because it was leaking, so I'm sure they probably didn't re-install it correctly or didn't plane the head correctly. I'll probably do a leakdown test as a last resort.

 

Try the comp test first like you said by putting some oil in the low cylinders to see if it raises the compression 150, 150, 150, 170 is right at the limits. I'd say you may have some oil going past the rings. Could also be bad valve guides/seals or oil leaks or a combo of everything

 

engines either burn or leak oil. it can't really go anywhere else.

 

Have you replaced the pcv valve? When it sticks it will burn oil by sucking it into the IM. Worth a few bucks to try it.