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  #11  
Old 01-03-2018, 01:11 PM
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DanH DanH is offline
 
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Quote:
Originally Posted by jabarr View Post
This is the most comprehensive study I’ve come across. Although only one aircraft oil was included, it is quite educational covering all aspects of oil technology. Very interesting about the temps that the oils are expected to run vs what we strive for in our world—-
It’s a very long read.

https://540ratblog.wordpress.com/201...-test-ranking/
The author may be a very intelligent guy, but the page is so polluted with rant that I don't think I can choke it down.
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  #12  
Old 01-03-2018, 01:14 PM
jabarr jabarr is offline
 
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Yeah, he’s kind of full of himself but there is some useful info.
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  #13  
Old 01-04-2018, 07:04 AM
BillL BillL is offline
 
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Default FYI -

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Originally Posted by bret View Post
I once had a conversation about oil with an oil guy, I asked about the multi weight oil, he had a very educated complex explanation but the one part I remember is that with a multi weight oil, you start off with a thin base oil, and then add the viscosity improvers to make it thicker when it gets warmer. so to do this you have the thin base oil, then subtract the amount of base oil to add the long chain viscosity improver additive that is not oil and you have less base oil lubricant. My experience has been the single wt W100 holds viscosity better at high temps than the multi weight oil.... but that's just one example with my setup.
The oil guy at my company told me many years ago that the VI (viscosity improvers) would precipitate out of the oil if it got contaminated with gasoline and then get filtered out by the oil filter. I have seen that happen on my auto in long periods of sub zero weather- but this was before adoption of EFI systems. VI loss results in a loss of viscosity, down to the lower number. It also results in a delayed reading of oil pressure on cold starts since the VI creates a higher restriction on the oil filter. VI would make the filter paper look glossy.

Disclaimer - I don't know if this is still the case as oil the oil companies are continually changing the formulations and learning how to address new issues. But, it could be related to your experience.
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  #14  
Old 01-04-2018, 07:13 AM
BillL BillL is offline
 
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Quote:
Originally Posted by jabarr View Post
Yeah, he’s kind of full of himself but there is some useful info.
Yes, but limited to the wear materials that is in his field of experience. On the remainder, DanH nailed it for me.

Regarding wear materials - - SwRI did some very interesting real time wear studies with radioactive materials 40 years ago showing wear during start ups and load changes were the worst, orders of magnitude worse. I 'm pretty sure some of this was published in SAE papers back in late 70's and 80's. These tests were some of the reasons that truckers were recommended not to shut off their engines very often.

Also, gives me pause for the modern auto engines (mine!) that want to stop-and-restart and every stop light.
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  #15  
Old 01-04-2018, 09:19 PM
6 Gun 6 Gun is offline
 
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Default oil update

540 Rat has posted an oil analysis of the Aeroshell 15-50W at the top of section 4 showing additives.
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  #16  
Old 01-06-2018, 07:04 PM
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Harvey Harvey is offline
 
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Location: I live on an airpark in South East Queensland, Australia
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Absolutely. More oil in the fuel, the greater the chance of detonation. I've seen reports that with some of the latest direct injection auto engines, a different oil formulation may be required due to the way the fuel is reacting with the oil in these motors, and why there has been some unexplained engine damage due to detonation....
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  #17  
Old 01-06-2018, 09:51 PM
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grubbat grubbat is offline
 
Join Date: May 2012
Location: Ga
Posts: 555
Default Marvel in the fuel

I wonder if marvel oil in the fuel also reduces octane and reduces detonation margin?

Quote:
Originally Posted by PerfTech View Post
....Actually the presents of oil (even in small amounts) in the fuel,
or in the combustion process, reduces the octane. This reduction
can allow detonation to begin. Once started, it can be self propagating,
snowball, and be very destructive. Thanks, Allan...
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