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Thread: 2.5 Turbo - Fuel oil dilution?

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    Registered Member Lbear's Avatar

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    2.5 Turbo - Fuel oil dilution?

    Any reported fuel oil dilution issues on the 2.5 turbo?

    With the Honda CRV turbo oil fuel dilution causing so many problems. I was wondering if Mazda had any issues with their turbos?

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    Quote Originally Posted by Lbear View Post
    Any reported fuel oil dilution issues on the 2.5 turbo?

    With the Honda CRV turbo oil fuel dilution causing so many problems. I was wondering if Mazda had any issues with their turbos?
    Probably worth a check on the CX-9 forum. They’ve been out for 3? Years now and are a better test.

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    Registered Member SignatureCX5's Avatar

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    There's a post on the CX-9 forum that had they results from oil analysis done by Blackstone Labs. Fuel in oil was less than 25% of normally acceptable levels. That one report indicates the 2.5T doesn't have a fuel dissolution problem.

    Because they engine was out for 3 years and no real issues reported is why I bought they CX-5 2.5T without worrying about potential unknown engine problems. Same goes for the reliability of the A6 reliability with the increased torque. I'd say the power train is solid.

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    Quote Originally Posted by Lbear View Post
    Any reported fuel oil dilution issues on the 2.5 turbo?

    With the Honda CRV turbo oil fuel dilution causing so many problems. I was wondering if Mazda had any issues with their turbos?
    Doubtful. The CX9 was the testbed for that engine and I have never heard a peep.

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    Quote Originally Posted by SignatureCX5 View Post
    There's a post on the CX-9 forum that had they results from oil analysis done by Blackstone Labs. Fuel in oil was less than 25% of normally acceptable levels. That one report indicates the 2.5T doesn't have a fuel dissolution problem.

    Because they engine was out for 3 years and no real issues reported is why I bought they CX-5 2.5T without worrying about potential unknown engine problems. Same goes for the reliability of the A6 reliability with the increased torque. I'd say the power train is solid.
    With a lot of t transmissions, it's RPM that kills them. I know in the LS1 world, you can put some power on a 4L60E, but if you throw a cam in the car instead of the bottle, you'll kill it dead ASAP shifting at 6500rpm even with similar power and less shockloading like with the juice. This is part of why I'm not really caring about the "low rpm" the thing performs at.

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    Registered Member Anchorman's Avatar

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    The turbo diesel has stopped diluting oil since the 2017 model thanks to redesigned pistons and rings. If that has been transferred to the 2.5T it should be the same.

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    got a not very promising analysis: https://www.mazdas247.com/forum/show...=1#post6647360

  8. #8
    Registered Member yrwei52's Avatar
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    Arrow 2.5 Turbo - Fuel oil dilution?

    Quote Originally Posted by crimeariver View Post
    It's the first time to me seeing an oil analysis on a 2.5T with oil dilution issue. On the other hand we did see several reports that when they check the oil level on their 2.5T, the oil level is over the "MAX" mark. It could be caused by over-fill from factory, or the oil dilution? Only time can tell.

    I don't agree Castrol GTX Magnatec is a "cheap" (bad) oil though. It's a full synthetic oil and 5W-30 is the recommended viscosity. It's API SN PLUS/ SN, ILSAC GF-5, and GM dexos1® Gen 2 certified.

    I also don't believe 87-octane gas has anything to do with your oil dilution issue either. We shall see with your next oil analysis which should confirm many things. Please keep us posted.

    Quote Originally Posted by crimeariver View Post
    Got an analysis for my 2.5T from oil analyzers... aaaand 5% fuel in 3350 miles.. ouch!

    The oil happened to be a cheap Castrol GTX magnatec. If I understand correctly, it should not affect fuel levels? Better oil should have just maintained the viscosity better.
    Possibly more relevant fact was that I ran only 87 gas this time, as a low interval experiment
    Switching to 91 and AmsoilOE, will check again in 3500.

    At the same time got a report for a q5 with 70+k miles. Only 1.6% over 9500 miles. Most of the mileage was rough due to carbon buildup.

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    Quote Originally Posted by yrwei52 View Post
    It's the first time to me seeing an oil analysis on a 2.5T with oil dilution issue. On the other hand we did see several reports that when they check the oil level on their 2.5T, the oil level is over the "MAX" mark. It could be caused by over-fill from factory, or the oil dilution? Only time can tell.

    I don't agree Castrol GTX Magnatec is a "cheap" (bad) oil though. It's a full synthetic oil and 5W-30 is the recommended viscosity. It's API SN PLUS/ SN, ILSAC GF-5, and GM dexos1® Gen 2 certified.

    I also don't believe 87-octane gas has anything to do with your oil dilution issue either. We shall see with your next oil analysis which should confirm many things. Please keep us posted.
    I agree, Castrol Magnatec is an excellent oil. You got the sample from a perfectly clean container, right?

  10. #10
    Registered Member yrwei52's Avatar
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    Arrow 2.5 Turbo - Fuel oil dilution?

    Quote Originally Posted by crimeariver View Post
    And I put your UOA to the following CX-5 thread and hope you don't mind:

    SkyActiv Oil Analysis Thread

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    Quote Originally Posted by SignatureCX5 View Post
    There's a post on the CX-9 forum that had they results from oil analysis done by Blackstone Labs. Fuel in oil was less than 25% of normally acceptable levels. That one report indicates the 2.5T doesn't have a fuel dissolution problem.

    Because they engine was out for 3 years and no real issues reported is why I bought they CX-5 2.5T without worrying about potential unknown engine problems. Same goes for the reliability of the A6 reliability with the increased torque. I'd say the power train is solid.
    Exactly. Even the hotter EU diesel cx5s dont have trans issues, and torque is what a trans sees along with rpm.

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