Shell Rotella T6 15W-40?

2011 Nismo#91 · 12-02-2020, 05:36 AM

Yeah those aren't even close to the temps in the cylinders. It's not burn off it's blow by that is the cause of oil consumption in these engines.

"Air ventilationMain article: crankcase ventilation system
During normal operation, a small amount of unburned fuel and exhaust gases escape around the piston rings and enter the crankcase, referred to as "blow-by". If these gases had no controlled escape mechanism, the gasketed joints would leak (as they "found their own way out"); also, if the gases remained in the crankcase and condensed, the oil would become diluted and chemically degraded over time, decreasing its ability to lubricate. Condensed water would also cause parts of the engine to rust. To counter this, a crankcase ventilation system exists. In all modern vehicles, this consists of a channel to expel the gases out of the crankcase, through an oil-separating baffle, to the PCV valve, into the intake manifold. In a non-turbo engine, the intake manifold is at a lower pressure than the crankcase, providing the suction to keep the ventilation system going. A turbo engine usually has a check valve somewhere in the tubing to avoid pressurizing the crankcase when the turbo produces boost.

If an engine is damaged or enters old age, gaps can form between the cylinder walls and pistons, resulting in larger amounts of blow-by than the crankcase ventilation system can handle. The gaps cause power loss, and ultimately mean that the engine needs to be rebuilt or replaced. Symptoms of excessive blow-by include oil being pushed up into the air filter, out the dipstick, or out the PCV valve. In rare cases of serious piston or ring damage, the oil filter housing's sheet metal can even burst at its seam."

This is why when excessive oil consumption was determined in engines the solution wasn't to get heavier oil but to replace the engine.

Rusty · 12-02-2020, 02:24 PM

Quote:

Originally Posted by 2011 Nismo#91

Yeah those aren't even close to the temps in the cylinders. It's not burn off it's blow by that is the cause of oil consumption in these engines.

"Air ventilationMain article: crankcase ventilation system
During normal operation, a small amount of unburned fuel and exhaust gases escape around the piston rings and enter the crankcase, referred to as "blow-by". If these gases had no controlled escape mechanism, the gasketed joints would leak (as they "found their own way out"); also, if the gases remained in the crankcase and condensed, the oil would become diluted and chemically degraded over time, decreasing its ability to lubricate. Condensed water would also cause parts of the engine to rust. To counter this, a crankcase ventilation system exists. In all modern vehicles, this consists of a channel to expel the gases out of the crankcase, through an oil-separating baffle, to the PCV valve, into the intake manifold. In a non-turbo engine, the intake manifold is at a lower pressure than the crankcase, providing the suction to keep the ventilation system going. A turbo engine usually has a check valve somewhere in the tubing to avoid pressurizing the crankcase when the turbo produces boost.

If an engine is damaged or enters old age, gaps can form between the cylinder walls and pistons, resulting in larger amounts of blow-by than the crankcase ventilation system can handle. The gaps cause power loss, and ultimately mean that the engine needs to be rebuilt or replaced. Symptoms of excessive blow-by include oil being pushed up into the air filter, out the dipstick, or out the PCV valve. In rare cases of serious piston or ring damage, the oil filter housing's sheet metal can even burst at its seam."

This is why when excessive oil consumption was determined in engines the solution wasn't to get heavier oil but to replace the engine.

That's

Think about how much pressure is needed to split a oil filter open.

The stock oil pump on the Z puts out over 115 psi already on a cold start.

2011 Nismo#91 · 12-03-2020, 05:56 AM

Quote:

Originally Posted by Rusty

That's

Think about how much pressure is needed to split a oil filter open.

The stock oil pump on the Z puts out over 115 psi already on a cold start.

It was probably a Fram filter.

Katana29 · 12-03-2020, 01:50 PM

So just making sure here.......

This engine was built by Rebello Racing and has around 20K miles on it. It has been very well maintained and it was recommended that either 0w-40 or 10w-40 oil be used, as it has forged internals that are looser than stock. I actually bought the car off a member (look up ban25's track journal for the specific car).

I have run both these oils and the consumption rate is night and day, with the 10w-40 burning off at less than half the rate and oil analysis samples coming back cleaner.

Like I said, the engine runs cooler and the valvetrain is definitely quieter with the 10w-40.

So I here what you guys are saying but the engine seems to prefer the thicker oil and that's why I'm confused.

The 15w-40 T6 has very similar properties to the 10w-40 but has a significantly higher flash point so I thought logically it should burn off slower. I know I've got blow-by and that's fine, it's supposed to have a bit of that. But the fact that the oil analysis, consumption, and temps seem to say the same thing..... I would think there would be other factors at play.

Katana29 · 12-03-2020, 08:14 PM

Anyone with a built motor have suggestions?

12-02-2020, 05:36 AM	#1 (permalink)
2011 Nismo#91 A True Z Fanatic Join Date: Mar 2011 Location: NJ Posts: 2,413 Drives: slowly Rep Power: 40571	Yeah those aren't even close to the temps in the cylinders. It's not burn off it's blow by that is the cause of oil consumption in these engines. "Air ventilationMain article: crankcase ventilation system During normal operation, a small amount of unburned fuel and exhaust gases escape around the piston rings and enter the crankcase, referred to as "blow-by". If these gases had no controlled escape mechanism, the gasketed joints would leak (as they "found their own way out"); also, if the gases remained in the crankcase and condensed, the oil would become diluted and chemically degraded over time, decreasing its ability to lubricate. Condensed water would also cause parts of the engine to rust. To counter this, a crankcase ventilation system exists. In all modern vehicles, this consists of a channel to expel the gases out of the crankcase, through an oil-separating baffle, to the PCV valve, into the intake manifold. In a non-turbo engine, the intake manifold is at a lower pressure than the crankcase, providing the suction to keep the ventilation system going. A turbo engine usually has a check valve somewhere in the tubing to avoid pressurizing the crankcase when the turbo produces boost. If an engine is damaged or enters old age, gaps can form between the cylinder walls and pistons, resulting in larger amounts of blow-by than the crankcase ventilation system can handle. The gaps cause power loss, and ultimately mean that the engine needs to be rebuilt or replaced. Symptoms of excessive blow-by include oil being pushed up into the air filter, out the dipstick, or out the PCV valve. In rare cases of serious piston or ring damage, the oil filter housing's sheet metal can even burst at its seam." This is why when excessive oil consumption was determined in engines the solution wasn't to get heavier oil but to replace the engine. __________________ GTR TT 493Whp/431lbft, Ecutek, Southbend 6puck,Quaife, RPM RollBar 4Point, R888R, JRZ RSPro F(10R/10C) R(10R/6C) 1000f500r inlbs+150inlbs Tender, SPL everywhere.Full Specs

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12-03-2020, 01:50 PM	#4 (permalink)
Katana29 Base Member Join Date: Aug 2020 Location: Florida Posts: 89 Drives: 2009 370Z Rep Power: 6	So just making sure here....... This engine was built by Rebello Racing and has around 20K miles on it. It has been very well maintained and it was recommended that either 0w-40 or 10w-40 oil be used, as it has forged internals that are looser than stock. I actually bought the car off a member (look up ban25's track journal for the specific car). I have run both these oils and the consumption rate is night and day, with the 10w-40 burning off at less than half the rate and oil analysis samples coming back cleaner. Like I said, the engine runs cooler and the valvetrain is definitely quieter with the 10w-40. So I here what you guys are saying but the engine seems to prefer the thicker oil and that's why I'm confused. The 15w-40 T6 has very similar properties to the 10w-40 but has a significantly higher flash point so I thought logically it should burn off slower. I know I've got blow-by and that's fine, it's supposed to have a bit of that. But the fact that the oil analysis, consumption, and temps seem to say the same thing..... I would think there would be other factors at play.

12-03-2020, 08:14 PM	#5 (permalink)
Katana29 Base Member Join Date: Aug 2020 Location: Florida Posts: 89 Drives: 2009 370Z Rep Power: 6	Anyone with a built motor have suggestions?