M1 0W-40 3 Track days Mx5 / Miata (Extend Drain?)

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Hi, Link to UOA for M1 0w-40... M1 0W-40 UOA This after 3 track days (say 400km total) and around 1000km of road driving. Vehicle is 2001 Mazda Mx5 / Miata. OEM mazda oil filter. Total km on vehicle is approx. 70,000km. At the track it's between 5000rpm and 7200rpm. The road km are just driving to/from various tracks, mostly on the freeway, at say 3000rpm. UOA looks ok to me. The fuel dilution is a touch odd, but I did idle the car for a while to warm it up before doing the oil change so perhaps that is it. Looking to extend the drain interval, so perhaps try 5 track days next? What do you think? Cheers.
 
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There is what looks like a lot of fuel, but then you spent a number of miles in the rich part of the fuel map while tracking. Other than that, it looks good. I'd try those five track days and then see what the oil looks like. I'll bet that you'll see even more fuel, but that didn't seem to cause any harm in this UOA.
 

Ned_Loh

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Thanks for the replies. Will try 5 or track days and re-test. Ok, so the fuel dilution could be from the rich fuel map at high RPM. I think (but I'm not 100% sure) the ECU switches from closed loop to open loop at above 4000rpm so that makes sense. Thinking about the fuel dilution for a minute...After 3 track days I'm at 1.8. At what point does fuel dilution become a problem? Cheers.
 
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Originally Posted By: Ned_Loh
Thanks for the replies. Will try 5 or track days and re-test. Ok, so the fuel dilution could be from the rich fuel map at high RPM. I think (but I'm not 100% sure) the ECU switches from closed loop to open loop at above 4000rpm so that makes sense. Thinking about the fuel dilution for a minute...After 3 track days I'm at 1.8. At what point does fuel dilution become a problem? Cheers.
There's a few schools of thought when it comes to fuel dilution. Personally I don't see fuel dilution as a problem unless it's thinned the oil enough to compromise film strength. Considering you've gone thicker than oem you have compensated for elevated oil temps and even with fuel dilution I think there's enough viscosity reserve in the chosen oil to be a non issue. What are the max oil temps experienced while tracking the car. A member here with an SRT 300 uses the same oil you are and even with oil temps in excess of 300f the used oil analysis showed nothing abnormal,so knowing that if you aren't pushing the oil to that extreme I think your fine. SteveSRT is the members name. Pm him. I'm sure he'd share his data and experience with you. Overkill also has a lot of experience with that oil too,in various engine platforms so he'd be a good guy to pick his brain as well.
 

Ned_Loh

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So I've done another oil analysis after 6 track days this time. Lab is concerned about level of silicone and fuel dilution. The silicone has gone from 13 after three track days to 24 after six track days. Sounds proportionally plausible. Lab caution limit is 20 and high is 35. Any comments please? The fuel dilution has gone from 1.8% after three track days to 4% after six track days. Sounds proportionally plausible. Lab caution limit is 1 and high is 2. Viscosity at 100c still looks ok. As posted above I am pretty sure this is because of time spent in the upper RPM and rich area of the fuel map. Any comments please?
 

Ned_Loh

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Originally Posted By: bulwnkl
Check your intake tract, and watch for coolant loss. Change the oil sooner.
pondering this a bit more and reading this site. If the high silicon was from dirt or coolant ingestion wouldn't some of the other markers be higher? Cylinder head was replaced just before the first UOA, so I wonder if the Si is still leaching out from some of the sealers or gaskets used. I guess all I can do is change a little earlier (say 4 or 5 track days) next time and see. If the number trends down I may be able to increase the OCI back to 6 track days. With regard to the fuel dilaution at 4%. Whilst not great it is possibly not an issues as nothing is showing signs that the film strength has broken down?
 
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When you race, you are in open loop mode. In other words the ECU is dumping as much fuel as the injectors/pump can be programmed to provide. It makes sense you have fuel dilution issues when opening it up. What kind of air filter do you use? The Si is from your intake.
 
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That's not how open loop works. Open loop at high throttle is an excess of fuel for increased power and, even more-so, reduced temperatures and the attendant reduction in propensity for detonation. This over-fueling is programmed after much testing and is not some fuel dump as you suggest. That said some power can often be had by leaning the fuel mixture from factory calibration. I second those who state air filtration should be checked. I would use an OEM filter and air box if longevity is a primary concern. Since there is no money or trophies to be had running track days I would leave the K&N and the like to the spec racers.
 
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Originally Posted By: Joshua_Skinner
That's not how open loop works. Open loop at high throttle is an excess of fuel for increased power and, even more-so, reduced temperatures and the attendant reduction in propensity for detonation. This over-fueling is programmed after much testing and is not some fuel dump as you suggest. That said some power can often be had by leaning the fuel mixture from factory calibration. I second those who state air filtration should be checked. I would use an OEM filter and air box if longevity is a primary concern. Since there is no money or trophies to be had running track days I would leave the K&N and the like to the spec racers.
The OEM tunes are usually too rich at wide open throttle. He should check out a miata forum to find out more.
 

Ned_Loh

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Originally Posted By: DoubleWasp
That's some nasty fuel dilution. I'd do a compression test.
Last compression test was around the time of the first UOA. It was fine. I've got nothing to suggest ring seal has deteriorated. Doesn't use oil. Nevertheless I will do another when I change plugs which are due soonish.
 

Ned_Loh

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Originally Posted By: Joshua_Skinner
That's not how open loop works. Open loop at high throttle is an excess of fuel for increased power and, even more-so, reduced temperatures and the attendant reduction in propensity for detonation. This over-fueling is programmed after much testing and is not some fuel dump as you suggest. That said some power can often be had by leaning the fuel mixture from factory calibration. I second those who state air filtration should be checked. I would use an OEM filter and air box if longevity is a primary concern. Since there is no money or trophies to be had running track days I would leave the K&N and the like to the spec racers.
The UOA after the first three tack days was on the factory airbox and OEM mazda paper filter. I did build a coldside intake/pod type thing about 3-4 track days ago so the last UOA from 6 track days would be a combination of OEM and my coldside intake. The fact that the silicon levels seem consistent in that 6 track days level is in proportion to the 3 track day level I don't think the issue is in the filter. I did replace the head a little while ago and wonder if the silicon used to seal up/under the cam caps could be causing the high reading. Engine also got new head gasket and cam seals etc at the same time. If it is silicon leaching from the mentioned places I would expect it to trend down over next UOA.
 
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