These are from another site about 2004 and 2005. They are by a person who said they are in the oil or automotive industry in Europe. I find them interesting and would like to hear what the BITOG folks think.
Quote:
HTHS is one of the most missunderstood characterisrics of oil. Having an extreme high HTHS value gives no security at all. I don't understand why people don't understand this.
Quote:
HTHS is a virtual dynamic viscosity at 150°C and a shear rate of 20 m/sec. It was "invented" due to the fact at the beginning of the 80's engines failed with oil of an HTHS < 2,0.
During a SAE congress in the 80's, all members agreed, that the available data showed that an HTHS > 2,5 is fair enough for every engine on the market in those days.
High HTHS values give you a fuel penalty. Depending on your engine, you will experience a higher fuel consumption of 2% if you use an oil with HTHS of 5 instead of 2,9.
Either your engine is durable, or it is not. If it is durable, high HTHS values don't give you a "safety margin". Thats especially true for your normal car, and that's also true for Diesel engines.
Quote:
To understand the situation today, you have to understand what happened in the past. Early XW-30 formulations where by far not as capable concerning wear protection as they are today. It is believed and commonly accepted by mechanical engineers (not by Lube Engineers...) that the conrod bearings of high RPM engines need high viscosity / HTHS oils to survive.
But "lessons learned" from the past with these early formulations are still very deep in the heads of the engineers at Porsche, Alfa, Ferrari etc.
Mechanical Engineers are a conservative, tough crowd...
Quote:
HTHS is one of the most missunderstood characterisrics of oil. Having an extreme high HTHS value gives no security at all. I don't understand why people don't understand this.
Quote:
HTHS is a virtual dynamic viscosity at 150°C and a shear rate of 20 m/sec. It was "invented" due to the fact at the beginning of the 80's engines failed with oil of an HTHS < 2,0.
During a SAE congress in the 80's, all members agreed, that the available data showed that an HTHS > 2,5 is fair enough for every engine on the market in those days.
High HTHS values give you a fuel penalty. Depending on your engine, you will experience a higher fuel consumption of 2% if you use an oil with HTHS of 5 instead of 2,9.
Either your engine is durable, or it is not. If it is durable, high HTHS values don't give you a "safety margin". Thats especially true for your normal car, and that's also true for Diesel engines.
Quote:
To understand the situation today, you have to understand what happened in the past. Early XW-30 formulations where by far not as capable concerning wear protection as they are today. It is believed and commonly accepted by mechanical engineers (not by Lube Engineers...) that the conrod bearings of high RPM engines need high viscosity / HTHS oils to survive.
But "lessons learned" from the past with these early formulations are still very deep in the heads of the engineers at Porsche, Alfa, Ferrari etc.
Mechanical Engineers are a conservative, tough crowd...
