Additive to combat fuel dilution

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My MazdaSpeed 6 is a direct injection motor. As seen by the numerous UOA's on this engine (Speed6, Speed3, CX-7), the oil seems to thin out by quite a bit during even a 3,000-4,000 mile interval.

Here is my last UOA. As you can see, there was only a trace amount of fuel detected in the two samples. Wear numbers weren't bad over the 4,300 mile interval. Because of that, I haven't been too worried about the dilution.

I've recently started taking much shorter trips with the car. These trips are in town and usually less than 5 miles. Because of this, I think my dilution numbers may be higher. I have used LC20 in the past, but that bottled was used up a few months ago.

I'm wondering if any of the current oil additives out there can help combat thinning of the oil due to fuel dilution? I have a couple bottles of Auto-RX still around (3-4 years old) that I could use, but I thought it was good for engine cleaning.

Anyone have any ideas? Is this just something I have to deal with by using shorter OCI's? I always use a quality oil such as Mobil 1 and PP is in stock right now in my garage.
 
I think the real answer is to continue regular UOAs to establish if your engine does have an issue with fuel dilution rather then worry about an issue you might not have.
 
Originally Posted By: Quest
IMHO I don't think your engine is suffering from fuel dilution problem (per your UOA report).

So why worry?

Q.


Blackstone does not measure fuel dilution directly. They use an Open Cup flashpoint measurement that appears to not be very sensitive. Just because Blackstone reports only trace dilution, does not mean that it is not there.
 
I actually meant to post this in the oil additive forum. I must have been browsing the fuel one instead.

My concern is how the oil is thinning down during the course of the interval. Being a little turbo engine, I was thinking thinning oil would be a bad thing.
 
Fuel dilution sort of has to be inferred when you look at a Blackstone report. If you see considerably lower viscosity and flashpoint numbers than they should be, and the sample smelled like fuel when you took it from the vehicle, there's a good chance that Blackstone might be underestimating the fuel content. Dyson Analysis would be a great crosscheck to see where you actually stand. That's what I have done. There are several other areas of a UOA that help to confirm the presence of fuel, and Terry will help you with this.

I don't know of an oil additive that helps wrt fuel dilution and viscosity shearing (40C and 100C), but some well established oils seem to work well for some applications and not others. Just when I see a UOA of something that held up well, there will be another one come along with the snot beat out of it.

I would say your best recourse would be to use a short OCI 3-5K miles with a SM rated oil and be happy. I don't know if fuel additives are part of the program for DI engines. If they are, limit them to your final tank of gas prior to your OCI. If you use Chevron fuel with Techron, watch out for elevated levels of Pb and Cu on your UOA's. If you don't have fuel dilution, this won't be a problem though.
 
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