My daughters 2006 4cyl auto accord has 175,000 miles of city/freeway driving. Last month when changing oil ,I found it 2 qts low at 7,000 miles on the oil. I did not investigate at that time. Now 5,000 miles later the oil light comes on and engine is 3 1/2 qts low. NO LEAKS! Tail pipe is carbon black. Power and driving is normal. Idle is perfect, and no ck engine light. I am thinking there is a vacuum valve malfunction that is allowing oil to be sucked into the intake. Where do I start? I am 50 years a diesel mechanic.

 

With that much oil loss, the engine is leaking or burning oil.

You can check the pcv valve to see if it is clogged up.

You may also want to look at the usual suspects for oil leaks around the engine. Oil filter, oil pan bolt, oil pressure sensor, valve cover, look around the timing chain cover. You can add some dye with the oil and use a UV light after some time to try and locate a leak.

 

Yup, pull the hose off the PCV valve and check for oil in it.

Here's the location.

 

AS s for leaks, NONE. I checked the intake air tubing and it is dry inside. There is a hose , top of valve cover, driver side going to a valve of some sort, right on the intake air tube. A little oil in this hose right at the valve cover. No oil where this all enters the intake air tube. PS: Air filter is clean.
Thanks Doc for the pic of PCV valve

 

That hose to the intake is the other half of the PCV system. It's supposed to draw air from the airfilter, to make up for what is sucked out of the crankcase through the PCV valve. Having a little oil in there is kinda normal. A lot of oil in that hose is a sign of the PCV valve clogged up.

 

Changing the PVC valve and will watch to see if oil consumption stops. Thanks for all the replies.

 

Make sure your daughter checks the oil level frequently and that she has some oil in the trunk to top off when needed.

I know on my old accord, I had a leaking pressure sending unit and it wasn't obvious that it was the source of my oil leak at the time.