Subject: Re: [Tigers] Oil and Filters...more questions..

From: [email-masked]
Date: Tue, 30 Jul 2013 11:37:53 -0400 (EDT)

Mayf,
I you decide on Mobile 1 you should check out availability at  Costcos and 
Walmart.  Yes, Walmart. When I drove a Mercedes the dealer said  use nothing 
but Mobile 1, 0W-40.  Got it at Walmart in 5 qt. contains and  was cheaper 
than any place I could find.
Mark L

In a message dated 7/30/2013 10:48:43 A.M. Eastern Daylight Time,  
[email-masked] writes:

Thanks  to everyone, I am a lot more informed on oil and filters. The 
plurality of  recommendations for oil was Mobile 1.  Ok, works for me. 
However,  within the Mobil 1 oil line up spectrum, there are quite a 
number of oils  in many different weights. The oil needs to be able to do 
its job under a  lot of stress: acceleration of teh car and pushing the 
air up a steeper  and steeper aero hill.  It needs to be able to carry 
the heat away  from the internal rotating and sliding parts.  I was once 
told by a  local Las Vegas NASCAR motor builder that the pump needed 
should be   a high volume pump, not a high pressure one, so that lots of 
oil could be  pushed through the bearing clearances. It made sense to 
me.  However,  the replies I got had oil recommendations from a light 
weight multi grade  oil to heavy single ot at least a very low multi with 
hight viscosity  upper grade: Such as 0W 30 to 0W 50 weights.  Ok, those 
are available  and some of them are down right expensive.  I am still 
lacing some  information, lol.

My motor specs are basically OEM: stock rod and  journal bearing 
clearances, rod to rod clearances are OEM, etc. Valves use  bronze 
guides, etc. I have a high volume pump. But, I am missing the logic  and 
engineering behind the recommendations for the oil grades (hey, what  can 
I say, I am an old engineer). Experience plays a large part or the  
recommendations, I know.   Do the Sprint Cup cars use 0w 50  weight oil?  
Or do they use lower viscosity multi grade like 0W 30 or  even 0W 20?  
Either way, why?  Same for light airplane motors;  Those puppies are at 
work the whole time they are in the air. What oils do  they use and 
why?    These are the kinds of things I would like  to know regards oils..

For the filters, Mobil 1, Pure one and WIX were  recommended. I cut a WIX 
apart and it appeared to be well made and had  specs that said it could 
remove particle sizes down to approximately (I  think I remember) 25 
microns.  To refresh, a micron is one millionth  of a meter.  There are 
25400 microns per inch or one micron is  0.00003934 inches.  So a filter 
than CAN remove (doesn't say will!)  remove a 25 micron particle size or 
so means that it might let one through  that is just under 0.001 inches.  
Seems to me that that is pretty  large given some of the rotating 
clearances.  A lot of the filters  said 60 microns!  Now, I am guessing 
that there is a balance between  the flow capability and particle size so 
the sizes are compromises. Seems  to me that if the motor is contributing 
bits and pieces of that size, that  it is or may be not long for the 
world.  I like the idea of using a  screen with a small mesh before great 
filter and that between the two it  would remove most junk.  But is that 
over kill? The screen can tell  me what or if things are starting to come 
apart.

Right now, I am  leaning towards Mobil 1, 5W 30 Truck & SUV full 
synthetic oil used  with a good filter such and the Royal Purple, WIX or 
Mobil 1  filters.  I know that yo all use as a group the full spectrum of 
oil  and filter products, so why do you use them? I like technical 
responses  rather than anecdotal ones however, experience and the 
situation under  which the experience was gained is important.

Any more replies and  responses here?  Maybe your comments and thoughts 
will save some  one's expensive motor...

anyhoo, thanks for listening...

still  learning

mayf

--  
______________________________
drmayf
Worlds Fastest Sunbeam,  period.
204.913 mph flying mile
210.779 mph exit  speed
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From: Mark Rense <[email-masked]>
Date: Tue, 30 Jul 2013 15:04:39 -0400

Dr. Mayf,
I did some Tribology work many years ago, so that along with many years of
racing have given me a small amount of knowledge.

The oil's main purpose is to keep moving metal parts from touching. It's
secondary purpose is to remove heat. A crankshaft rotating in a plain
bearing generates much heat, some conducted down from the combustion
chamber, the majority from the oil itself as the hydrodynamic boundary
layers shear. A big part of the viscosity question centers on pumping
losses through each bearing race. There is both the static pressure and the
dynamic pressure that builds up, so the amount of oil that can be pumped
through a given journal at a given clearance varies as the temperature and
RPM increase. Generally most engines I build are "clearanced" to use a
10W-30 oil. This means each journal is measured and clearances are set to
flow a given amount of oil at a given pressure/temperature. You always want
some pressure build-up inside each journal, otherwise the oil would not
suspend the rotating mass. However, too much resistance to flow and the oil
stagnates and overheats. The balancing act is between the static oil
pressure, the load, the running temperature, the journal surface area and
the viscosity of the oil. I  have to make some assumptions first, mostly
that I am restricted to 60 PSI maximum hot static pressure at the pump, and
that the journals all behave in a uniform manor. For most American V8s
there is so much collective knowledge that simple look-up tables are
available to help with clearances. For more exotic engines some testing
would need to be done. You want to be able to support your dynamic load and
also move enough oil through to keep everything cool.

If the oil viscosity for a given bearing clearance is too low you will
create heat from an insufficient film thickness which results in
metal-to-metal contact, generating even more heat until the bearing
surfaces braze together. This is amplified when impulse energy is
introduced, such as power-shifting. Too high a viscosity will also allow
heat to be generated, this due to the internal fluid friction and shearing
created within the oil. This localized heating will thin the oil out inside
the bearing so it pushes out quickly, but the cooler, thicker oil behind it
cannot flow fast enough in to replace it so the bearing starves and you
wipe the bearing. Another problem with too-high viscosity is cavitation.
The bearing creates both high and low pressure zones, these occur on each
side of the oil's minimum film thickness, and can cause oil cavitation in
the bearing from the rapid expansion of dissolved air, water and/or fuel.
The bubbles will implode and you will lose the oil film, again wiping the
bearing. This is called cavitation pitting, and it happens in racing
engines that run high-viscosity oils.

OK, so Dr. Mayf you say that you are all OEM clearances, but the OEMs
generally designed for oil temperatures around 130 C or so, and that is
10W-30 territory. Do you monitor oil temperature on a run? A LSR engine
will be pulling WFO at high RPM for a long time, so localized oil
temperatures will rise much higher than that. Are you running an oil
cooler, I hope? A cooler will help stabilize the system making it more
predictable.

The synthetic oils designed for racing will remain in their viscosity class
for much longer at elevated temperatures (200 C+) before breaking down, so
for that I recommend that you start with a top-line synthetic like the
Mobil 1 Racing 0W-30 or Red Line 30WT Racing oil. These oils also have a
lot more various zinc additives to further protect the rotating shiny
parts. A thicker oil like the Mobil 1 Racing 0W-50 may not flow fast enough
in your bearings to dump heat as quickly, but if the ambient is high (40
C+) then that would be a good choice. As to using a high-flow oil pump,
there is no need if the clearances are good and the right oil is used,
otherwise you are just creating parasitical power loses by moving extra oil
through the pressure-relief by-pass. Besides, most after-market racing
pumps flow more than an OEM pump anyway. And I recommend Wix filters, they
seem to have remained consistent in quality.

Could be worse, the Formula 1 guys pay over $500 a liter for special Mobil
1 Racing oil!

Hope this helps.

Bugz

[email-masked]