Marine Lubrication
#1383
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What is nitration?
#1384
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Nitration: The combustion chambers of engines provide one of the few environments where there is sufficient heat and pressure to break the atmospheric nitrogen molecule down to two atoms that can react with oxygen to form nitrous oxides (NOx). This becomes a major problem for some engines, especially natural gas engines. Because natural gas engines run so lean, they have higher combustion temperatures and a lot more NOx are formed than with other types of fuel. When nitrogen oxide products enter the lube oil through normal blow-by, they react with moisture present in the lube and become very acidic and rapidly accelerate the oxidation rate of the oil.
Really doesn't apply to Gearlubes, but definitely motor oils.
Really doesn't apply to Gearlubes, but definitely motor oils.
Last edited by 07DominatorSS; 12-06-2008 at 12:06 PM.
#1387
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Attached are my engine oil analysis since the motor was new, one per season. Unfortunately my engine is a moving target since I have made modifications each winter which are noted at the bottom of the oil analysis history sheet. After each modification there was a recalibration phase of the Mercruiser PCM555 ECU during which time was spent running boat with ECU calibration at certain rpm's being richer than optimum always occuring at low rpm's and mid range rpm's. A/F target is 12.5. The stock 496HO produced moderate to heavy transum sooting. The next two seasons was about half that. This last season the tune was more in the low 13's A/F with lowest in the low 12's and transum soot was almost non existant. This fact makes the latest high gasolene content in the oil extermely confusing to me. Prior to installing the Amsoil oil for this most recent season I broke in the engine rebuild for a total of three hours with two oil and filter changes, one after 15 min engine flush and the other after 3 hours run time with stock Merc 20W40 oil. The high gasolene content during the preceeding season was expected since early ECU cal was in the 10's and flooded the engine followed later by an intake lifter failure that ran the engine on seven cylinders flooding that cylinder with raw gas for a time. As noted I have run stock Merc, Mobil 1 V Twin and Amsoil Racing oils. Analysis of the virgin Amsoil and Mobil 1 are also included. I tend to spend a lot of boat hours cruising at 2500 - 3000 rpm's and wake boarding at similar speeds.
You knowledgable comment on the results is solicited especially relative to any red flags I should be aware of.
You knowledgable comment on the results is solicited especially relative to any red flags I should be aware of.
#1388
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I should clarify that the Merc 20w40 oil analysis provided was not the original oil in the motor but installed after a few hours running on the original oil (boat purchased in the Fall so short season).
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Nitration: The combustion chambers of engines provide one of the few environments where there is sufficient heat and pressure to break the atmospheric nitrogen molecule down to two atoms that can react with oxygen to form nitrous oxides (NOx). This becomes a major problem for some engines, especially natural gas engines. Because natural gas engines run so lean, they have higher combustion temperatures and a lot more NOx are formed than with other types of fuel. When nitrogen oxide products enter the lube oil through normal blow-by, they react with moisture present in the lube and become very acidic and rapidly accelerate the oxidation rate of the oil.
Really doesn't apply to Gearlubes, but definitely motor oils.
Really doesn't apply to Gearlubes, but definitely motor oils.
Ken