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Old 11-12-2015, 10:48 AM   #1
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Default Blackstone UOA - High Lead? How bad is it?

I just received my second set of Blackstone UOA results and again, the oil is showing high lead content. The car is a 2000 SE, stock motor with 77K on the motor. I was using Mobil 1 5W30 full synthetic for both of these changes, the first sample showed lead levels at 19ppm after 1000 miles. Everything else seemed really great.

This second sample on oil I ran for the full Autox season showed 68ppm after 2300 miles. Typically the car would sit for 1-4 weeks between being run, and I had not disabled the clutch interlock at this time. Trips to the Autox site were about 10 miles each way, drive the event, drive home. There were also a few longer drives to and from national events this year, but that is it.

I'm very concerned about the high lead content. I changed the oil at the end of the season and it still seemed fairly clean, I have since put in Valvoline VR1 synthetic 10w30. Oil pressure is a little lower now on start up vs the Mobil 1 5w30, but only a few psi (maybe 5-8 lower). I have also removed the clutch/starter interlock so now I can start the engine without murdering the thrust bearing.

How concerned should I be? The only metal that I see that is high is lead. Are the stock mazda crankshaft and rod bearings lead only, or are they at multilayer design?

If these were an ACL bearing, I'd be seeing Copper, Tin, Nickel and elevated Lead; is that correct?
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Old 11-12-2015, 12:01 PM   #2
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I don't know the composition of the factory bearing, but I seriously doubt it's a tri-metal, so you may not see the other components that are in an ACL tri-metal.
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Old 11-12-2015, 12:42 PM   #3
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I was bummed by the high lead in the results, I wasn't planning on needing to pull the motor out until next winter when it was going to get at least a built bottom end. I have all the bottom end components except the seals and a boundary engineering pump. I suppose I could wait on the head work that I have parts for to keep the cost down. Then I'd be ready once the rest of the parts for your turbo kit are finished. Even if just do the bottom end this winter, I'd be SOL for running in street prepared and have to move to SSM early with no turbo and no aero.
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