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Old 06-16-2010, 10:12 PM
  #46  
blown 87
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Originally Posted by ptuomov
You mean one on blowers vs. turbos? I am working on it, give me a moment...
Make sure you get in which is better a positive displacement or a dynamic type of supercharger is better suited to the 928.
Old 06-16-2010, 10:16 PM
  #47  
ptuomov
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Originally Posted by blown 87
Make sure you get in which is better a positive displacement or a dynamic type of supercharger is better suited to the 928.
Given that this question has such a clear-cut, unambiguously correct answer, I will of course work it in there.
Old 06-17-2010, 10:08 AM
  #48  
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Don't forget the talking monkey...
Old 06-17-2010, 10:36 AM
  #49  
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Originally Posted by NoVector
I'm confused--over 1/2 the NASCAR field uses Mobile 1.
Wait, what? Seems doubtful because there's no need for all that detergent in a track car. I know the Joe Gibbs teams have their own oils made for them (and they sell most of these, but not all).

Nobody here has tried Motul 300V? It seems like really good stuff, seems to have the least viscosity breakdown of anything I've tried, but somehow I've never had an oil analysis container handy when changing it out of my engine (I've been trying a few different things).

Joe Gibbs Hot Rod Oil sticks to things really really well, but it does seem to thin out a bit when you get it really hot.
Old 06-17-2010, 11:26 AM
  #50  
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Brad Penn 20W-50 in the race car and also in my street cars. Great oil, GREAT price.
Old 06-17-2010, 11:30 AM
  #51  
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Oh Goody an oil thread.

Well on my GTS I always used Mobil 1 15W 50 from about 2002 until 2007. Then the consensus changed and it was not good to use Mobil 1 due to the level of ZDDP being reduced due to its effect on cats in modern cars.
So I moved to the Diesel Delvac oil which all said was good.
At this point I started to get low oil pressure at tick over in hot ambient conditions. This concerned me so I looked for an alternative.
I wanted a good quality synthetic oil with lots of ZDDP. Again a consensus pointed me towards Royal Purple as being the “bees knees” when it comes to oil.

I use RP 20W 50 and I am very happy with it.
My new cams have caused my idle to be lower than normal so sometimes I see 15 to 22 psi at idle on a hot day but never see the low pressure warning light on the dash or the digital low pressure warning.

So here is the question.
Why are so many seeing low pressure at idle in high ambient conditions recently (say last 18 months) when this was not a problem before.
Have all the oils changed in some way? Not a what is the best oil but more of a generic question????????/

Roger
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Old 06-17-2010, 11:40 AM
  #52  
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Originally Posted by ROG100
I use RP 20W 50 and I am very happy with it.
My new cams have caused my idle to be lower than normal so sometimes I see 15 to 22 psi at idle on a hot day but never see the low pressure warning light on the dash or the digital low pressure warning.
Hotter cams that idle lower? Sounds like the best of all worlds! Wonder who will be running the same cams in the near future? ;-)

Originally Posted by ROG100
So here is the question. Why are so many seeing low pressure at idle in high ambient conditions recently (say last 18 months) when this was not a problem before. Have all the oils changed in some way? Not a what is the best oil but more of a generic question????????
The standard answer would be engine wear. If the bearings wear to increase clearances, the leak is larger and (as long as the pump is operating in the mode in which the relief valve is not cycling) this would lead to a lower oil pressure. It's the standard answer, but I don't know if it's the correct answer.
Old 06-17-2010, 11:51 AM
  #53  
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Originally Posted by ptuomov
Hotter cams that idle lower? Sounds like the best of all worlds! Wonder who will be running the same cams in the near future? ;-)
Don't hot cams always idle lower until you make an adjustment to raise the idle to counter the cam?
Old 06-17-2010, 11:52 AM
  #54  
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The formulas for a type of oil can and do change, with the cost of the base stocks and additive packs.

For most oil companies as long as it just meets the API specs they do not care if it is better or worse.
Old 06-17-2010, 11:53 AM
  #55  
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Originally Posted by ROG100
So here is the question.
Why are so many seeing low pressure at idle in high ambient conditions recently (say last 18 months) when this was not a problem before.
Have all the oils changed in some way? Not a what is the best oil but more of a generic question????????/

Roger
Here's what I can come up with for now:
  • Different formulations that lead to lower temps for thermal breakdown
  • People are maybe more "tuned in" to reading their oil pressure on hot days/hard running - I know I am.
  • I supposed Tuomou's comments could be valid, but I doubt this is the reason.
  • William Shatner said it should be so.
Old 06-17-2010, 12:01 PM
  #56  
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Originally Posted by marlinspike
Don't hot cams always idle lower until you make an adjustment to raise the idle to counter the cam?
You're of course right. I assumed that this was after sharktuning the idle speed to meet the requirements. If the car would work and drive well in all conditions at that new lower idle speed with hotter cams, one could ask the question why was the idle speed so high with the stock cams in the first place. (Another issue is that if the ISV were really operating in close loop, shouldn't it in theory regulate the idle speed to the set level? Closed loop theory seems to have turned into something else in practice at some point...)

End of digression, back to the regularly scheduled programming.
Old 06-17-2010, 12:13 PM
  #57  
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Originally Posted by ptuomov
End of digression, back to the regularly scheduled programming.
Should I be using green or pink coolant?
Old 06-17-2010, 12:14 PM
  #58  
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Originally Posted by Hacker-Pschorr
Should I be using green or pink coolant?
Just match the color of your intake manifold.
Old 06-17-2010, 12:17 PM
  #59  
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Originally Posted by ptuomov
You're of course right. I assumed that this was after sharktuning the idle speed to meet the requirements. If the car would work and drive well in all conditions at that new lower idle speed with hotter cams, one could ask the question why was the idle speed so high with the stock cams in the first place. (Another issue is that if the ISV were really operating in close loop, shouldn't it in theory regulate the idle speed to the set level? Closed loop theory seems to have turned into something else in practice at some point...)

End of digression, back to the regularly scheduled programming.
Can I digress a bit more?
So a person ought to raise the idle after hotter cams? Does this mean that when I overshot the idle (made it about 100rpm higher than factory) making my K-jet car work with hot cams I actually did the right thing?
Old 06-17-2010, 12:18 PM
  #60  
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I am talking about a lot of cars here - I used my GTS as an example.
Jim M's GTS is having the exact same issues as mine. We both have the same cams and both have RP in the engine. Had the same issues using Mobil 1 and Jim also with the Brad Penn IIRC.
My 87 S4 has the same issues using RP. I hear others having the same issues using lots of other different types of oil.

I would always see 29psi at idle on any of my later cars on any day in any weather.

Andrew - you are right I am looking more often now.

Why have we moved from 15W 50 to 20W 50? I should be good using 15W 50 according to Porsche and there oil use chart.

For hot ambient temperatures what oil will give good pressure – say 2 bar 29psi at idle. Is it a question of supplier or the viscosity/makeup?


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