SM-PU 5W30, 2348 Miles, CX7 DISI Turbo

[BobThe]

So when checking my Oil, it smelled more like a gas can than used oil. Being paranoid about all I have been reading about DI motors and shearing, I decided to do a change and send a sample in to Blackstone. It was after it had been warmed up on a 15 mile or so run and the sample was taken half way through the drain. I didn't do a TBN since it only had 2348 miles on the change. I figured there would be plenty left. MI/HR on Oil 2348 MI/HR on Unit 6263 Sample Date 12/11/11

Code:

ALUMINUM    3
CHROMIUM    0
IRON	    15
COPPER	    19
LEAD	    1
TIN	    0
MOLYBDENUM  43
NICKEL	    0
MANGANESE   49
SILVER	    1
TITANIUM    0
POTASSIUM   3
BORON	    281
SILICON	    4
SODIUM	    3
CALCIUM	    2771
MAGNESIUM   35
PHOSPHORUS  649
ZINC	    695
BARIUM	    0
	
SUS Viscosity @ 210°F	49.4
cSt Viscosity @ 100°C	7.08
Flashpoint in °F	330
Fuel %          	1.8
Antifreeze %	        0
Water %                 0
Insolubles %	        0.3

It looks to me like it sheared the oil down to a 20wt after 2300 Miles? Am I reading that right? I typically drive ~ 10 miles each way to work and back daily with some longer trips on the weekends and occasional 300 Mile runs to Michigan. Let me know what you guys think.

 

[Turk]

Shear city. Plus, you have a good nose.

 

[Lead Shoes]

Sheared to a 20 in 2k?????!! Shear city indeed...

 

[JAG]

Viscosity loss from fuel dilution isn't "shearing". Shearing is viscosity loss from mechanically stressing the oil. That's a lot of fuel dilution and it doesn't take long for it to stabilize at that high concentration so changing the oil early does little good from a fuel dilution perspective. Piston rings and bores were probably still breaking in thereby allowing more blow-by and fuel dilution so that should improve. I'd probably mix some 5W-30 with the 5W-20 to raise the viscosity.

 

[volk06]

Wow that really worked the PU, sheared to a 20wt, moderate levels of wear metals but still good for a breaking in engine and 1.8% fuel. That engine is rough oil! I'd use a cheaper oil like PP or QSUD for 3OCI and sample to see if your fuel dilution improves.

 

[cp3]

I like JAG's take on things but we have seen other reports with as much or more fuel that have not been this thin.

 

[BobThe]

Originally Posted By: JAG

Viscosity loss from fuel dilution isn't "shearing". Shearing is viscosity loss from mechanically stressing the oil. That's a lot of fuel dilution and it doesn't take long for it to stabilize at that high concentration so changing the oil early does little good from a fuel dilution perspective. Piston rings and bores were probably still breaking in thereby allowing more blow-by and fuel dilution so that should improve. I'd probably mix some 5W-30 with the 5W-20 to raise the viscosity.

I don't understand what you are telling me relating to adding some 5W-30. It started out as a 5w-30 and ended up like this in 2300 miles. I did a full change on it (still using SM PU 5W-30 from the stash). Maybe you were thinking I only took a sample? Either way, would you say I should run it longer (maybe next time a 3k OCI) and see if the fuel dilution looks the same?

 

[JAG]

Oops small screen I'm using caused me to think you used 5W-20. That is really high loss of viscosity! I'd either stick with it and sample again or maybe add some M1 0W-40 if viscosity is a concern but that is undesirable from a mixing brands perspective. PU 10W-30 should be a little more shear stable than 5W-30 but not enough to keep the viscosity in the xW-30 bracket, IMO.

 

[OVERKILL]

Shear city. That's where we're heading. Dancing and singing til dawn! The magic that is direct injection.

 

[Eddie]

I run 5w30 PP in my CX7 turbo. My 6,000 mile OCI shows good wear values and the oil stays in grade with about 0.5% fuel on two UOAs. I don't understand why your fuel % is so high. The DISI engines run a stoichiometric A/F ratio except under high boast according to those folks who have method of checking it while running. I wonder if you have leaking injectors or something else causing this.

 

[WANG]

I did one UOA when I had a CX-7 and it had a significant amount of fuel in it, too. Seems pretty common for these. Good thing they have such a healthy sump capacity.

 

[Indydriver]

You're getting me worried about my Mazdaspeed3 which has 3,000 miles on it's first load of synthetic (PP). Dipstick also smells strongly of gas and the oil's black.

 

[addyguy]

I'm pretty sure I've read here that Mazda allows the use of 40-weight oils in their DI turbo engines. I'd use M1 0W-40 in it.

 

[qr25de]

Any of the 5w-30 Diesel oils would work fine with relatively low fuel dilution. The high fuel concentration is likely to be a result of a breaking-in direct injection and turbocharged engine.

 

[BobThe]

Not my concern anymore. I just traded it in on a 2011 Nissan Titan SV Crew Cab 4x4. I didn't like needing to gear up for a fight with the dealer / Mazda and I got a great deal. Turns out my company gets me invoice on Nissan's. I believe all of this oil shredding in this engine leads to the failures in the timing chains and VVT. My CX7 was within the TSB VIN range of those failures. From what I have read, they allowed the use of 40wt when you had exhaust smoke from failing seals in the turbo (Bandaid fix). Either way, I am back to a port injected engine. I know that I could be trading one problem for another, but the Nissan deal is right across the street instead of a haul to get to the Mazda dealer.

 

[steve20]

Did you get a gas card along with it?

 

[BobThe]

Well no, but the CX7 was getting 16-18 city using super unleaded and the Titan is getting 13-14 so far using regular unleaded. Not as good as the 7, but acceptable for the drive I have and the 7 was nowhere near what I would consider good either.

 

[doyall]

Originally Posted By: JAG

... changing the oil early does little good from a fuel dilution perspective. ...

Can you elaborate?

 

[JAG]

Originally Posted By: doyall

Originally Posted By: JAG

... changing the oil early does little good from a fuel dilution perspective. ...

Can you elaborate?

The fuel dilution rapidly reaches an equilibrium level, assuming the driving and ambient conditions don't change much. Let's simplify the situation to make it easier to conceptualize. Virgin oil is in the sump. Fuel gets added to the oil at rate x grams per hour of operation. Fuel dilution goes from zero to a steady y% during operation. It stabilizes when the rate of fuel evaporated equals the constant rate of fuel added. The higher the fuel dilution percentage, the higher the rate of fuel evaporation. I have not seen a correlation between OCI and fuel dilution in UOAs I've seen. I think equilibrium happens prior to 1000 miles in most cases.

 

[doyall]

Originally Posted By: JAG

The fuel dilution rapidly reaches an equilibrium level, assuming the driving and ambient conditions don't change much. ...

Then fuel dilution isn't a phenomenon that progressively worsens as time accumulates? It reaches a point rather quickly and remains relatively constant? So if one has an engine used under a fairly fixed set of operational parameters that is prone to fuel dilution, there is little that can be done about it reactively? The only solution is to be proactive, i.e., correct the cause?