Shell Rotella T6 - 5W40
Purolator PureONE filter

 

2014 running OEM Mobil I believe and the 2011 is running Redline 20/50.

 

I have the same thing!

Low RPMs, whine.

I thought it was my steering pump, and after it got rebuilt for leakage it didn't go away.
I was under the car when it was on jacks, idling, and its defiantly the compressor...

I used my stethoscope. its definitely the compressor. I don't know why or how, but i feel better if it fails (and doesn't seize) it will not blow my motor.

 

Hmmm i'll check the compressor when i'm under my car this weekend.

Even if th ecompressor does sieze, it won't break the engine.... It'll just break the belt. I had that happen on my 240sx. No AC and power steering is fun in texas in july

 

Haha I can imagine. Let me know what you find, it annoys the heck out of me, but I don't really want to swap it out.

Also, I was reading it had some sort of clutch assembly, maybe something is rubbing. Not sure...

 

An AC compressor uses a electromagnetic clutch assembly. That's how it "turns on" the actual compressor component, it electrifies a coil surrounding the driving shaft to pull the pulley into contact with the shaft which therefore spins the compressor. If the clutch assembly is bad then I could see it causing a noise, but there's an infinite amount of variables to an engine compartment noise. Could be a ton of things..

 

There are a number of threads on this. Sounds like it's the oil pump. Unfortunately a number of owners have been experiencing this for some time now. I even swapped out pumps and it didn't change. I can say it became more obvious after I installed a mishimoto oil cooler and the noise I belive transmits through it more than stock. Take a stethoscope and a friend, have your friend hold the rpm steady for you, and put the end of the stethoscope on the bottom of the timing chain cover and the noise should be near it's loudest. The oil pump is just behind this location. My car is most obvious at 2050 -2100 rpms. I'm finally just ignoring it.

 

Didn't have anyone available to rev the engine when i was working on it last weekend.

I changed all fluids, engine oil, t-case, tranny, and both fluids in rear diff. Noise is still there. I think i can say for certain it is not a drivetrain related noise. You're probably right about the compressor though. That's really odd that for some reason this mitsu compressor makes noises but no other manufacturer's does...... odd.....

In 4k miles i'll be changing my oil with the mobil 1 synthetic instead of my Rotella T6. I'll report if there are any changes then.

 

I'm running the full synthetic Mobil1 5w40 turbo diesel truck oil in my wife's mazdaspeed 6 because I thought the turbo was smoking and needed to use thicker oil. I called my mechanic while I was picking up the oil just to make sure it's ok to use. He said it's the same they just market it for turbo diesel trucks because it's an oil weight more commonly used in turbo diesel trucks. I could be totally wrong on this, just going on what my mechanic told me. I haven't noticed any additional noise in her car from using the oil though.