hello all, i have a mazda 6. 2004 with 3.0 5 speed. 148,000 on the clock. while back had loud clattering noise from motor. did the sea foam crap with no resuts. did the marval oil additive and after few miles quies as a mouse. 3000 miles later i get this loud ticking on top of motor, under valve covers. started using oil rapidly! changed oil and added marval oil additive again, and ticking has stopped but 1 quart every 50 miles and smokes like the devil!!! ideling or driving! 3 pvc valves, new pvc line... no change. oil on #6 plug. pistion is wet and shiny clean!!! did comp test on front 3. hot motor i got 118, 120, (126 on plug with oil) what is going on? no skipping or surging. to a blind man he would never know anything was wrong. hel

Update.... just did compression test on motor cold. All 3 cylinders hit 124. #4 plug no oil, #5 no oil, # 6 oil. But all 3 read the same psi.

 

Back in 2009 I had a compression test done on my 2006 V6 3.0 Mazda 6 and my values were 190. To me your values seem low. I would phone your local Mazda dealer service department and ask them what acceptable values are for your year of car. With that mileage and all that burning oil, your catalytic converters may be plugged. Plugged catalytic converters can cause pressure to back track to your engine causing severe damage. Mazda recommends changing the catalytic converters after 100,000 miles. http://www.villa-automotive.com/Reas...terFailure.htm (see the part on Oil entering).
You could have oil passing by the piston rings and/or the valve seals. The prognosis does not sound good. Please phone your local Mazda dealer for verification.

1 thing you could do to help it last longer is install a large oil catch can. This catches the oil from the PCV line before it goes in to the intake. This kit has a good explanation with pics, however it is small: OCC KITS MAZDA 6 - Performance Automotive Development LLC

Mazda and Mazdaspeed Oil Catch Can by Corksport

This one is large: *ISIS Universal Round Large 2L Oil Catch Can - Enjuku Racing Parts, LLC

You will have to drain them every trip (with your stats).

 

OP, sounds like your Oil Control Valves are bad. You may need to replace the engine. When was the last time you replaced your PCV Valve?

 

PVC has been changed week ago. Again! Putting car up for sale. I haven't the time or the money to deal with these issues.