Oil consumption way up with Mobil 1 0W-40
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From: The Great White North
W204 C63 Coupe, W166 ML350 BlueTEC, 928GT, Taycan GTS Sport Turismo, C5 Z06 & IS300 race cars
Burned off by the cats. When I said "cat-killer" I personally had OE primary cats killed at 50k miles in an M5 as a direct result of a high rate of oil consumption. It's the oil itself and the range of additives present in the oil and gasoline. This from Wikipedia:
Catalyst poisoning occurs when the catalytic converter is exposed to exhaust containing substances that coat the working surfaces, encapsulating the catalyst so that it cannot contact and treat the exhaust. The most-notable contaminant is lead, so vehicles equipped with catalytic converters can be run only on unleaded fuels. Other common catalyst poisons include fuel sulfur, manganese (originating primarily from the gasoline additive MMT), and silicone, which can enter the exhaust stream if the engine has a leak that allows coolant into the combustion chamber. Phosphorus is another catalyst contaminant. Although phosphorus is no longer used in gasoline, it (and zinc, another low-level catalyst contaminant) was until recently widely used in engine oil antiwear additives such as zinc dithiophosphate (ZDDP). Beginning in 2004, a limit of phosphorus concentration in engine oils was adopted in the API SM and ILSAC GF-4 specifications.
Catalyst poisoning occurs when the catalytic converter is exposed to exhaust containing substances that coat the working surfaces, encapsulating the catalyst so that it cannot contact and treat the exhaust. The most-notable contaminant is lead, so vehicles equipped with catalytic converters can be run only on unleaded fuels. Other common catalyst poisons include fuel sulfur, manganese (originating primarily from the gasoline additive MMT), and silicone, which can enter the exhaust stream if the engine has a leak that allows coolant into the combustion chamber. Phosphorus is another catalyst contaminant. Although phosphorus is no longer used in gasoline, it (and zinc, another low-level catalyst contaminant) was until recently widely used in engine oil antiwear additives such as zinc dithiophosphate (ZDDP). Beginning in 2004, a limit of phosphorus concentration in engine oils was adopted in the API SM and ILSAC GF-4 specifications.
Leaded gas hasn't been around for, what - 30 years now? And, you'd need ten times the ZDDP content in the oil that normally comes in oils with even with the highest levels of anti-wear additives to produce enough garbage to kill the cats in 50K miles. Yes, you will kill them sooner, but that means maybe in 20 years instead of 30. It was almost certainly a defect with your motor that caused you to burn too much oil that killed them, not the additives themselves.
M5 you say? An E34 with a Nikasil block by any chance?
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C63 AMG
You'd need to burn a LOT of oil to clog and kill the cats - as in going through a quart every 200 miles or so for several years. The only way you could use up that much oil is if your rings are shot or the cylinder walls scored, and you'd be seeing tons of blue smoke coming out the tailpipe every time you accelerate. Been there myself.
Leaded gas hasn't been around for, what - 30 years now? And, you'd need ten times the ZDDP content in the oil that normally comes in oils with even with the highest levels of anti-wear additives to produce enough garbage to kill the cats in 50K miles. Yes, you will kill them sooner, but that means maybe in 20 years instead of 30. It was almost certainly a defect with your motor that caused you to burn too much oil that killed them, not the additives themselves.
M5 you say? An E34 with a Nikasil block by any chance?
Leaded gas hasn't been around for, what - 30 years now? And, you'd need ten times the ZDDP content in the oil that normally comes in oils with even with the highest levels of anti-wear additives to produce enough garbage to kill the cats in 50K miles. Yes, you will kill them sooner, but that means maybe in 20 years instead of 30. It was almost certainly a defect with your motor that caused you to burn too much oil that killed them, not the additives themselves.
M5 you say? An E34 with a Nikasil block by any chance?
I did end up getting the motor replaced but it was never a "blue-smoker." Must have been those low-tension, low-friction rings.
Last edited by bhamg; Feb 19, 2015 at 03:20 AM.
