Oily stuff - 5W20

[Huw Powell]

Hi Mike,

You were following me just fine.  I run 50 weight synthetic oil that is 
as thin as 5 weight would be at -25 dF.

The "winter" weight is the multi-viscosity part, that makes cold starts 
much easier.  The "regular" weight is what the engine requires at 
operating temperature.

- Huw

On 12/4/2014 1:24 PM, Mike Claire wrote:
> Huw, I thought I was following you until you said you run 5W50 in your
> 90Q.  I thought your argument would be that anything less than "10" is
> too thin for cars of our vintage.
>
> If Rotella T6 5W40 for my S4 AAN is good, I'll do it as I already stock
> it for my '01 S8 4.2 V8.  My oil shelf's running out of room - different
> oils for all 5 cars and a tractor!
>
>
>
> Mike
>
> On Thu, Dec 4, 2014 at 9:23 AM, Huw Powell <audi at humanspeakers.com
> <mailto:audi at humanspeakers.com>> wrote:
>
>     John is correct.
>
>     The idea of looking at the numbers on oil and "deciding" whether or
>     not to use it makes no sense.
>
>     Engines are built to certain tolerances and require certain fluids
>     to function properly.
>
>     In the case of oil, there is a viscosity range recommended (which
>     may vary slightly depending on conditions), from a "cold" end that
>     allows sufficient flow for lubrication at start up to a "hot" end
>     that maintains enough viscosity for adequate pressure to be
>     developed at "running" temps.  Keep in mind that "running" temps are
>     pretty much the same no matter how (reasonably, like >= -40 deg)
>     cold the ambients are.
>
>     Just because a new weight range turns up on the shelf doesn't mean
>     it's a new good thing for your engine.
>
>     The "standard" used to be 10W40, with a few deviations, and a few
>     requirements for synthetics.
>
>     The standard for the last couple of decades has run towards 5W30,
>     with many calls for 5W20, 0W20, etc., often requiring OEM/dealer
>     sourced oil coming in the last decade.  These engines have far
>     tighter tolerances and thus build plenty of pressure with the
>     thinner oil, saving energy - and also, well, having tighter tolerances.
>
>     These simply are not correct for our cars.  If you aren't sure,
>     check your owner's manual and use either what it says, or try
>     something slightly thicker if you are consuming a lot (> 1 qt/1000
>     mi, or even >1 qt/tankful of fuel).
>
>     I like 5W50 synthetic for my 90Q - easy cold starts, no fears of it
>     getting too thin when I am in "oil-cooled" mode.
>
>     - Huw
>
>
>     On 12/3/2014 11:46 PM, John Larson wrote:
>
>         On 12/3/2014 2:32 PM, Tihol Tiholov wrote:
>
>             To keep list traffic going, here's a general question.
>             Anyone with
>             thoughts, experience, etc. re: this oil? Isn't it too narrow
>             a temp.
>             range,
>             esp. for the Graet White North? I don't, nor intend to use
>             it, just
>             curious, since it's taking over the shelves at FLAPS.
>
>             Tihol
>
>         It's important to remember that modern "thin" oils are required
>         for use
>         in modern engines.  Tolerances are tighter, oil passages are
>         smaller,
>         and the engines are designed to utilize thinner oils to aid in fuel
>         economy.  Older designs, such as all the I5 engines and nearly
>         all their
>         contemporaries don't do well with thinner oils because the
>         passages are
>         relatively large and clearances are loose. The results of using oils
>         made for the newer designs are lowered oil pressure, and most likely
>         increased oil consumption.  Porsche, as well as Mercedes, use
>         0w20 as a
>         factory fill.  Scary, huh? Knowledgeable techs and shops put
>         5w20 in 'em
>         ...
>
>         John
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