Polyester vs PAO Base Oil

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Wouldn't RL's POE basestock make it a more durable oil for extended drains then an oil with a PAO basestock or is there more to it then that?
 

MolaKule

Staff member
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A POE base oil has better thermal and oxidative stability better than a mineral or mostly PAO base oil. Unless you have an additive package with long-term (long drain) reserves, the formulated POE oil might not be useful past 5-7k. It takes both a good base oil and additive package to make an extended interval fully formulated oil. [ October 30, 2003, 05:26 PM: Message edited by: MolaKule ]
 
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354
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Chicago
Isn't water building up and contaminating the oil a larger factor for polyester oil than PAO? I remember this being a possible difference between the two types of base oils and Redline even mentioning why they recommend maximum of year intervals without UOAs. I realize this of course would depend on cold start driving intervals, weather and engine condition.
 

MolaKule

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The esters used today are not hygroscopic. I don't know how this myth got started, but it is not from fact. The esters used in motor oils are about as hygroscopic as mineral oils. Detergents have been found to actually reduce friction and increase lubricity.
 
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Polyolester type lubricants are hygroscopic and therefore easily absorb moisture. To avoid this, special filter/dryers are incorporated in systems designed for HFC refrigerant gases. From an AirConditioning site.
 
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354
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Chicago
Yeah, that's right Jason. I don't know what I was thinking with longer than year intervals recommended by an oil manufacturer. But I do know I have read about PAOs dealing with water better than polyolesters. Whether it is 100% true fact, I don't know. I did find this on the mobil1.com website however: Q: Red Line Oil claims to have 100 percent polyolester base stocks. Are these different or better than the base stocks used in Mobil 1 with SuperSyn™? A: We are very familiar with polyolesters. In fact, we manufacture them and use them in our aviation jet engine oils such as Mobil Jet Oil II® and Mobil Jet Oil 254® and in our refrigeration compressor lubricants, where the polyolesters are utilized for their compatibility with new HFC refrigerants. Polyolesters are indeed excellent at high-temperature oxidation stability and low volatility. However, our work on automobile engines and jet engine designs has shown that polyalphaolefins (PAOs) offer the best all-around performance for gasoline engines due to their: * Being completely compatible with conventional oils and gasoline engine seals. * Providing both low- and high-temperature performance. * Providing a stable oil in the presence of water and moisture. * Having anti-rust capabilities.
 
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254
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Calgary AB
My experience with POE has been on aero engines and there industrial derivatives. I have witnessed 50 gallons of very expensive POE lube oil being tested and being very acidic. It had to be dumped. I know a company now EPT in Calgary that claim they can recover the TBN on these oils. I don't know. This oil will run at 300°F for hours and remain a light translucent straw (it will eventually oxidize and become dark) colour for many hours. Unless you need the high temperature performance, not think know! It will also react badly with water.
 
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