Will Oil Make A Difference "Yes it Does"
10-14-2009, 10:59 AM
#1
Race Car
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Will Oil Make A Difference "Yes it Does"
86 S/C 5-speed
Since installing the Super Charger my normal operating temperature run higher the before. I changed to Val 10/40 and the pressure during hot idle and under 2500 rpm's was lower than I felt comfortable with.
With under a few hundred miles since the Val change I decided to change to Mobil-1 20/50 here are the results.
http://picasaweb.google.com/tampapix...eat=directlink
Since installing the Super Charger my normal operating temperature run higher the before. I changed to Val 10/40 and the pressure during hot idle and under 2500 rpm's was lower than I felt comfortable with.
With under a few hundred miles since the Val change I decided to change to Mobil-1 20/50 here are the results.
http://picasaweb.google.com/tampapix...eat=directlink
10-14-2009, 11:34 AM
#2
Three Wheelin'
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Hi 
Hmmm.....I have noticed before American 928 owners mentioning oil pressure at 2 bar ish....
I and all other UK 928 owners would be horrified if our pressure dropped that far....
Why do UK cars run at around 5 bar (hot idle) ???
Not just mine by the way , but all of them.....
For oil I use Full synthetic 15/50 by the way....
All the best Brett
Hmmm.....I have noticed before American 928 owners mentioning oil pressure at 2 bar ish....
I and all other UK 928 owners would be horrified if our pressure dropped that far....
Why do UK cars run at around 5 bar (hot idle) ???
Not just mine by the way , but all of them.....
For oil I use Full synthetic 15/50 by the way....
All the best Brett
10-14-2009, 11:42 AM
#3
My oil pressure is similar and I use Mobil 20/50 too. Hot idle (700rpm) will have pressure just under 2 bar, but any revs at all and the pressure immediately climbs towards 5. Running pressure is always 4+.
10-14-2009, 11:47 AM
#4
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Idle (hot) on UK cars is around 5 and any acceleration takes it to 5.5 plus....
If I EVER saw 2 bar...at idle , I would instantly turn off my engine as I would suspect oil pump failure or major oil loss....
Now....WHY are your cars running at 2 bar ??? different oil filters with different oil pressure relief valves maybe ??
Anyone know ?
All the best Brett
10-14-2009, 11:53 AM
#5
Team Owner
Brett you wouldnt have to shut off the engine unless the low oil pressure light/ ! came on.
That said it seems that different cars have different readings some have the gauge pegged at 5 and still others run at 4.8 cold or hot, with idle readings at 1.5 to 3 so i think this is just the differences in the gauges and senders.
I would guess that more than a few of the senders have been replaced with new versions and the guages dont read what they used to due to age
That said it seems that different cars have different readings some have the gauge pegged at 5 and still others run at 4.8 cold or hot, with idle readings at 1.5 to 3 so i think this is just the differences in the gauges and senders.
I would guess that more than a few of the senders have been replaced with new versions and the guages dont read what they used to due to age
10-14-2009, 11:56 AM
#7
Administrator - "Tyson"
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Yes.
Like most of your posts, your data is highly suspect.
https://rennlist.com/forums/4572511-post63.html
https://rennlist.com/forums/4542163-post22.html
https://rennlist.com/forums/4547963-post34.html
https://rennlist.com/forums/4552401-post45.html
https://rennlist.com/forums/4558196-post53.html
Typical Brett, whatever your car does must translate to every other 928 in the world, especially other UK 928's.....
Like most of your posts, your data is highly suspect.
https://rennlist.com/forums/4572511-post63.html
https://rennlist.com/forums/4542163-post22.html
https://rennlist.com/forums/4547963-post34.html
https://rennlist.com/forums/4552401-post45.html
https://rennlist.com/forums/4558196-post53.html
Typical Brett, whatever your car does must translate to every other 928 in the world, especially other UK 928's.....
Trending Topics
10-14-2009, 12:07 PM
#8
Racer
Err Brett et al...
5 bar is 72psi if any of my cars showed that much pressure at hot idle I would worry.....
Does all that oil fit in the top of the motor? Because at that hot idle pressure it surely is not in the bottom end.
5 bar is 72psi if any of my cars showed that much pressure at hot idle I would worry.....
Does all that oil fit in the top of the motor? Because at that hot idle pressure it surely is not in the bottom end.
10-14-2009, 12:08 PM
#9
Administrator - "Tyson"
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You forgot, he's in the eastern hemisphere where toilets flush sideways.
10-14-2009, 12:09 PM
#10
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If my oil pressure was reading 5 bar on hot idle I would shut it off, because I would know I was not getting a proper reading or had some other problem.
That is not normal and sounds like a open in the circuit.
That is not normal and sounds like a open in the circuit.
Hi
Idle (hot) on UK cars is around 5 and any acceleration takes it to 5.5 plus....
If I EVER saw 2 bar...at idle , I would instantly turn off my engine as I would suspect oil pump failure or major oil loss....
Now....WHY are your cars running at 2 bar ??? different oil filters with different oil pressure relief valves maybe ??
Anyone know ?
All the best Brett
Idle (hot) on UK cars is around 5 and any acceleration takes it to 5.5 plus....
If I EVER saw 2 bar...at idle , I would instantly turn off my engine as I would suspect oil pump failure or major oil loss....
Now....WHY are your cars running at 2 bar ??? different oil filters with different oil pressure relief valves maybe ??
Anyone know ?
All the best Brett
10-14-2009, 12:31 PM
#11
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Hi
I have driven many 928s in the UK, AND ALWAYS the pressure is between 4 and 5 bar at hot idle...and increases to 5 plus as soon as I pull away or increase the revs.....
Just in my family we have 2...my S2 and my brothers earlier S2...both have identical pressures.....I have driven many others all the same.....
IS this a difference between 32v and 16 v ???
Is this a difference between UK and US oil filters ???
Is this a difference between UK and US oils ???
A technical reason might be nice for an answer instead of implying I am lying.....which I am NOT !
All the best Brett
I have driven many 928s in the UK, AND ALWAYS the pressure is between 4 and 5 bar at hot idle...and increases to 5 plus as soon as I pull away or increase the revs.....
Just in my family we have 2...my S2 and my brothers earlier S2...both have identical pressures.....I have driven many others all the same.....
IS this a difference between 32v and 16 v ???
Is this a difference between UK and US oil filters ???
Is this a difference between UK and US oils ???
A technical reason might be nice for an answer instead of implying I am lying.....which I am NOT !
All the best Brett
10-14-2009, 12:31 PM
#12
I hate to disagree, Brett, but I'm in London and have a UK-supplied 1991 S4. When cold, the oil pressure gauge pegs at 5 bar the whole time, but when the engine's hot it shows a steady 2 bar at idle, climbing to 5 bar by about 2750rpm. As far as I was aware that's standard behaviour for the 928, full stop. If mine showed 5 bar even at a hot idle I'd be suspecting a dodgy gauge or sender.
Indeed, I recall reading of someone who walked away from a potential 928 purchase because a devious previous owner had superglued the needle on the gauge so it always read 5 bar!
As an aside, and in a (probably doomed) attempt to say something on-topic, I've tried both 10W50 and 10W40 oils, and have never seen any appreciable difference in the behaviour of the oil pressure gauge. That said, I don't drive the car on track and the past few years the summer temperatures have struggled to crack 75 Fahrenheit...
Indeed, I recall reading of someone who walked away from a potential 928 purchase because a devious previous owner had superglued the needle on the gauge so it always read 5 bar!
As an aside, and in a (probably doomed) attempt to say something on-topic, I've tried both 10W50 and 10W40 oils, and have never seen any appreciable difference in the behaviour of the oil pressure gauge. That said, I don't drive the car on track and the past few years the summer temperatures have struggled to crack 75 Fahrenheit...
Last edited by PreacherCain; 10-14-2009 at 12:32 PM. Reason: kyeborad malfunction.
10-14-2009, 12:37 PM
#14
Three Wheelin'
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I hate to disagree, Brett, but I'm in London and have a UK-supplied 1991 S4. When cold, the oil pressure gauge pegs at 5 bar the whole time, but when the engine's hot it shows a steady 2 bar at idle, climbing to 5 bar by about 2750rpm. As far as I was aware that's standard behaviour for the 928, full stop. If mine showed 5 bar even at a hot idle I'd be suspecting a dodgy gauge or sender.
Indeed, I recall reading of someone who walked away from a potential 928 purchase because a devious previous owner had superglued the needle on the gauge so it always read 5 bar!
As an aside, and in a (probably doomed) attempt to say something on-topic, I've tried both 10W50 and 10W40 oils, and have never seen any appreciable difference in the behaviour of the oil pressure gauge. That said, I don't drive the car on track and the past few years the summer temperatures have struggled to crack 75 Fahrenheit...
Indeed, I recall reading of someone who walked away from a potential 928 purchase because a devious previous owner had superglued the needle on the gauge so it always read 5 bar!
As an aside, and in a (probably doomed) attempt to say something on-topic, I've tried both 10W50 and 10W40 oils, and have never seen any appreciable difference in the behaviour of the oil pressure gauge. That said, I don't drive the car on track and the past few years the summer temperatures have struggled to crack 75 Fahrenheit...
I believe you, maybe its because yours is a 32v......I have driven a lot more 16v than 32....
My oil pressure did drop once when I put in 0-40 oil and it dropped to just under 4....so I instantly drained it and put back in my normal 15/50...
My pressure has run at 5 at idle for nearly 5 years now so no appreciable problem.....and as every 928 I have driven has been the same, I just (maybe incorrectly) assumed it was normal....
Maybe we should start a poll on pressures...if nobody has done it by then , I will set one up tonight when back from work...
All the best Brett
10-14-2009, 12:50 PM
#15
Nordschleife Master
Oil pressure = flow times resistance.
Our oil pumps are displacement types, hot or cold, pump flow is the same at any given rpm.
Resistance is due to oil viscosity and clearances within the oil system, bearings and such.
Pressure above 5 bars and the pressure relief valve sends some of the oil flow back to the crankcase instead of through the engine.
The lowest safe oil pressure is the best.
Changes in idle temperature, my guess are related to some non oil, perhaps cooling issue.
Our oil pumps are displacement types, hot or cold, pump flow is the same at any given rpm.
Resistance is due to oil viscosity and clearances within the oil system, bearings and such.
Pressure above 5 bars and the pressure relief valve sends some of the oil flow back to the crankcase instead of through the engine.
The lowest safe oil pressure is the best.
Changes in idle temperature, my guess are related to some non oil, perhaps cooling issue.