Oil Pressure
and be careful of doing to much at one time..
01-30-2008, 01:22 PM
#11
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Your oil pressure goes down with old oil? I assume this is with Royal Purple 5W30? If so, the reports of Royal Purple 5W30 shearing is true I guess.
Not a bit concern to me, but interesting nonetheless.
Not a bit concern to me, but interesting nonetheless.
01-30-2008, 01:42 PM
#13
and all these chemicals will degrade overtime, heat will speed the process even faster.
Changing your oil every 3K miles is always a good thing. and yes it was RP 5w30. Have you not seen my plugs thread? You should know which grade I use.
01-30-2008, 01:54 PM
#14
Administrator
iTrader: (7)
I'll check my idle pressure when I leave here today. I got a range from 14 psi - 80 psi while driving today.
01-30-2008, 05:39 PM
#15
Got Another Rotary
Viscosity Index Improvers (VIIs) are the "additives" that work to maintain viscosity/thickness of the oil as it gets warmer to maintain the target viscosity at operating temp (20, 30 , etc.).
VIIs break down over time and do not perform as well - this process is called "shearing". As these VIIs breakdown, or shear, oil does thin out at it's operating temperature, so oil pressure will go down due to a worn out, thinner oil in which the VIIs are not working as well.
This is why viscosity at operating temp is measured as part of oil analysis - to compare to new oil and determine amount of shear during use.
Also, synthetics have a significant advantage over dino oils in this regard - they require much less, and sometimes no, VIIs to obtain the target oil viscosity range due to their better cold flow properties. Less VIIs means there is less to break down over time as base oil never looses its initial viscosity.
For all oils - small range oils, like 5W20, often require less VIIs and are less likely to shear than broad range oils, say 5W40, as they have/need less VIIs to create the target range.
01-30-2008, 05:54 PM
#16
Actually this is not exactly true.
Viscosity Index Improvers (VIIs) are the "additives" that work to maintain viscosity/thickness of the oil as it gets warmer to maintain the target viscosity at operating temp (20, 30 , etc.).
VIIs break down over time and do not perform as well - this process is called "shearing". As these VIIs breakdown, or shear, oil does thin out at it's operating temperature, so oil pressure will go down due to a worn out, thinner oil in which the VIIs are not working as well.
This is why viscosity at operating temp is measured as part of oil analysis - to compare to new oil and determine amount of shear during use.
Also, synthetics have a significant advantage over dino oils in this regard - they require much less, and sometimes no, VIIs to obtain the target oil viscosity range due to their better cold flow properties. Less VIIs means there is less to break down over time as base oil never looses its initial viscosity.
For all oils - small range oils, like 5W20, often require less VIIs and are less likely to shear than broad range oils, say 5W40, as they have/need less VIIs to create the target range.
Viscosity Index Improvers (VIIs) are the "additives" that work to maintain viscosity/thickness of the oil as it gets warmer to maintain the target viscosity at operating temp (20, 30 , etc.).
VIIs break down over time and do not perform as well - this process is called "shearing". As these VIIs breakdown, or shear, oil does thin out at it's operating temperature, so oil pressure will go down due to a worn out, thinner oil in which the VIIs are not working as well.
This is why viscosity at operating temp is measured as part of oil analysis - to compare to new oil and determine amount of shear during use.
Also, synthetics have a significant advantage over dino oils in this regard - they require much less, and sometimes no, VIIs to obtain the target oil viscosity range due to their better cold flow properties. Less VIIs means there is less to break down over time as base oil never looses its initial viscosity.
For all oils - small range oils, like 5W20, often require less VIIs and are less likely to shear than broad range oils, say 5W40, as they have/need less VIIs to create the target range.
01-30-2008, 08:06 PM
#18
Administrator
iTrader: (7)
here's a pic I JUST took as I pulled up to the house. 5w20
(excuse the crappy cell phone pic)
(excuse the crappy cell phone pic)
01-30-2008, 09:45 PM
#20
RX-8s Official Cool Guy
01-30-2008, 09:47 PM
#21
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01-31-2008, 06:57 AM
#24
the basic background to that are oil air bubbles break when the oil surface tension is exceeded and a way to improve that is to put impurities in the oil to give the surface weakspots. The impurities or 'antifoamant' agents are usually silicone and float around in the oil (not in solution). The have been know to be filtered out by filters sometimes and synthetic oils have a harder time with foaming because the oil lacks impurities to begin with.
01-31-2008, 04:50 PM
#25
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Actually this is not exactly true.
Viscosity Index Improvers (VIIs) are the "additives" that work to maintain viscosity/thickness of the oil as it gets warmer to maintain the target viscosity at operating temp (20, 30 , etc.).
VIIs break down over time and do not perform as well - this process is called "shearing". As these VIIs breakdown, or shear, oil does thin out at it's operating temperature, so oil pressure will go down due to a worn out, thinner oil in which the VIIs are not working as well.
This is why viscosity at operating temp is measured as part of oil analysis - to compare to new oil and determine amount of shear during use.
Also, synthetics have a significant advantage over dino oils in this regard - they require much less, and sometimes no, VIIs to obtain the target oil viscosity range due to their better cold flow properties. Less VIIs means there is less to break down over time as base oil never looses its initial viscosity.
For all oils - small range oils, like 5W20, often require less VIIs and are less likely to shear than broad range oils, say 5W40, as they have/need less VIIs to create the target range.
Viscosity Index Improvers (VIIs) are the "additives" that work to maintain viscosity/thickness of the oil as it gets warmer to maintain the target viscosity at operating temp (20, 30 , etc.).
VIIs break down over time and do not perform as well - this process is called "shearing". As these VIIs breakdown, or shear, oil does thin out at it's operating temperature, so oil pressure will go down due to a worn out, thinner oil in which the VIIs are not working as well.
This is why viscosity at operating temp is measured as part of oil analysis - to compare to new oil and determine amount of shear during use.
Also, synthetics have a significant advantage over dino oils in this regard - they require much less, and sometimes no, VIIs to obtain the target oil viscosity range due to their better cold flow properties. Less VIIs means there is less to break down over time as base oil never looses its initial viscosity.
For all oils - small range oils, like 5W20, often require less VIIs and are less likely to shear than broad range oils, say 5W40, as they have/need less VIIs to create the target range.
On BITOG there is debate over the 5W30 weight Royal Purple as members have shown that it shears through wear. For those of us changing oil every 3,000 miles though, I don't think it's a big deal. However, because of the longevity concerns, I use Mobil 1 5W30 in all cars that I maintain except for my RX-8 since they're all on 7,500-10,000 mile drain intervals.
nycgps, don't forget you were using Shell synthetic in your sparkplug thread and had previously used Mobil 1. I wasn't sure which oil you were reporting.