It's not a hi-jack when the OP is a one-and-done airhead, like the guy who started this thread.
^^ +1 ^^
My daughter's 2011 2.0L 3i has never used any oil whatsoever, with regular 7.5K OCIs, and an 11K extended oil change the last time. I've used only top-shelf 0W-20 full synthetic and Mazda filters, and regularly check the oil between changes.
I listened to it as she started it up at -1F this morning, and it sounded great. Nothing 'extra' from the engine, just a nice solid purring sound. I love that engine
Thanks for the feedback m3iguy;
Iím glad to hear youíve had good luck with 2011 2.0. The engine I got from the junk yard in PA is a 2011 2.0 w/ 111k miles on it. What kind of oil have you been using? Iím planning on using Castrol 0w-20 synth.
Which brings me to a question for all; since Iím new to the synthetic oil world, what should I start with when I run the engine through the brake in period? Do these Mazdaís come from the factory with synthetic oil and 0 miles on the engine? So youíre running synthetic for the first 5k miles?
Back to the ďdisappearing oilĒ issue:
As I was rambling in yesterdayís post, I was considering the PCV comment. I think this may be one of the key players in the overall issue. Iíll need to look at the design of the PCV and vacuum system and see if anything jumps out.
One of the other key players (IMHO) may be the fuel mixture. Iíll have to check the engine that threw a rod, but the one I got used from the junk yard was apparently running very rich. The cylinders looked like cylindrical mirrors. And the carbon build up was thick (in the areas where it would tend to not get blown off). Iíll need to check the VCU to make sure it has the appropriate code when we get it running again.
As I see it: (and Iím way open for suggestions and corrections here) the high mixture causes an excess in un-burnt fuel to deposit in the form of carbon. The carbon builds up (this happens relatively fast) to the point at which it flakes off during the combustion part of the cycle and gets stuck to the cylinder wall.
The piston comes up and collects the carbon which causes a build up along the perimeter of the piston (the compression ring). These larger particles do two things. 1: They get ground down and work their way throughout the ring grooves, eventually making their way to the oil ring and mixing with the oil (ever notice the black stuff that comes out when you change your oil?
Itís clear when it goes inÖ). And 2: Some of the larger particles get blown out of the combustion chamber; I believe causing pitting on the valve lands along the way. (I had to have my valves and valve lands cut because there were some really deep pits.)
Both of these processes will eventually lead to lose of compression. The lost compression into the crankcase (blow-by) will increase as the compression rings become restricted by the excess buildup of carbon between the ring and the piston ring groove surfaces. The buildup affects the combustion ringís tendency to spring back as the piston travels back up the cylinder. The affect is that it takes longer due to increased friction. When this happens the ring can no longer apply adequate pressure to the cylinder wall.
Lost ring pressure on the cylinder wall means the rings will start to float a little as the piston travels up. When this happens, some carbon (very small particles) will roll between the cylinder wall and the surface of the ring. (Thatís a very nice polishing method.) At the same time they are polishing the cylinder walls the rings are floating higher allowing larger carbon particles between the ring surface and the cylinder wall. Now weíre getting even more blow-by and lost compression.
Itís a vicious cycle that just keeps growing as the engine hours accumulate. Poor oil quality and a low quality oil filter (one that doesnít filter to a low enough micron level) coupled with longer than recommended OCIs will contribute to more and more blow-by creating the perfect storm; literally.
Now the crankcase is pressurized. Not so much that it blows your dip stick out, but higher than the PCV system was designed to handle. Where does all that extra air go? Back to the intake (I think
). But, now that itís traveling at a higher speed and volume; itís taking more oil vapor along for the ride.
And so weíre back to the beginning of the story; which is a lot of air, mixed with too much fuel, combined with some dirty air, mixed with too much oil, and the process starts all over again. But itís worse now.
Ok. Those are my thoughts for the day. I have to go pick up a used AC compressor for Old Blue and get back to the 2.0 waiting for me in the garage.