Ferrari Mailing List: Re: All about oil????

[Peter Pless (ferrarilist]

That all makes sense Hans...BUT...what if ferrari wasn't really concerned
with what happened at 212 deg, but more what happened at 260 deg on a very
hot day or on the track? Which if the reality is that the 50 mineral oil
drops to the same thickness at that temp as a 40 synthetic? That's really my
question. Is it possible that 50 is thicker than ferrari would like in a
perfect world because they had to protect the engine at 250+?

Does that make sense? 

-----Original Message-----
From: Hans E. Hansen [mailto:FList [at] hanshansen.org] 
Sent: Wednesday, 26 March 2008 11:51 AM
To: Peter Pless
Cc: The FerrariList
Subject: Re: [Ferrari] All about oil????

Well, remember, viscosity is viscosity - old or new, dino or synthetic.  So
the measured viscosity of a modern synthetic 5w40 when hot (I believe the
measurement temp is 212deg F - why it's related to water boiling temp is
anyone's guess....) is the same as the measured viscosity of 40 dino oil -
old or new - at that temp.  A 10W50 dino would be thicker than a 5w40
synthetic at the hot *measurement* temp, because it measures 50 while the
synthetic measures 40.  But if either were to get hotter, the synthetic
wins.

It's kind of an unfortunate rating system, because it's confusing.  The
viscosity number is just an assigned number based upon some measurements.
It's not an actual measurement.  That's why we are seeing some 0W30, etc.
oils coming out.  Even thinner oils are being made, but the old labeling
system won't really support them.  You'd have to label them "-10W30" or
somesuch, which is blatently stupid, as you can't have negative viscosity.

The old system was invented to label single weight dino oil.  20W, 30W, etc.
These oils had known temperature characteristics, so it was expected that
they would be thinner at elevated temp.  What happened is that somebody
invented viscosity improvers and looked for a way to label the 'new and
improved' oil.  So - if we take our new viscosity improved oil and compare
it at room temp to regular oil, we see, for example, that it is the same as
a 20W.  Now we heat up both our 'new and improved' oil as well as various
reference single weight oils.
Our new oil at 212deg behaves like 50W at 212deg.  Both are thinner, but our
improved oil when hot is like 50W when hot, and when cold it is like 20W
when cold.  So let's call it 20W50.

The so-called multiweight oils are a huge improvement.  In the old single
weight days, the manufacturer would specify, say, 20W.  Since the engine
usually is operated hot, this 20W, when thinned due to heat, was optimum.
But it was way too thick when cold.  And if the motor got too warm, say
towing a trailer or when raced, the oil thinned too much.  Racers typically
used 50W.  The multi viscosity oils allow for something that is much thinner
when cold, which is good, as it flows better.

I would definitely look at the 2nd number when comparing oils to
manufacturer's recommendations.  This is the viscosity at operating temp.
If Ferrari wanted 50W when hot, that's what I'm going to use.
You have some flexibility with the 1st number, as just about any oil is
probably too thick when cold.

Hans.

On 3/25/08, Peter Pless <ferrarilist [at] pless.com.au> wrote:
> Wait...that being the case, then maybe at a high temp, a 5w40 
> synthetic will be just as thick as a 10W50 mineral grade ferrari was 
> recommending in 1977!!!....with the advantage of it being thinner when 
> the engine's cold (which is a good thing)
>
> What do you think?
>
> I know carl jones ran 5W40 in his glass GTB and even though it's 
> broken due to some very bad fuel, the bores and bearings looked like 
> new after (I
> think) 70,000km!
>
> Maybe that's the answer?? When the oil gets really hot (and ferrari 
> has to protect its engine) the mineral 50 weight got much thinner than 
> the 40 weight synthetic??
>
> Does any of this make sense, or should I get more sleep?
>
>
>
> -----Original Message-----
> From: Hans E. Hansen [mailto:FList [at] hanshansen.org]
> Sent: Wednesday, 26 March 2008 11:17 AM
> To: Peter Pless
> Cc: The FerrariList
> Subject: Re: [Ferrari] All about oil????
>
> On 3/25/08, Peter Pless <ferrarilist [at] pless.com.au> wrote:
> > Ok...well that just scared the crap out of me!
> >
> > I'd still like to know what they'd specify for a 308 if it were made 
> > TODAY considering the advances in oil technology.
> >
>
> Sure, oil technology has come a long, long way.  But viscosity is 
> viscosity, old or new.  What has changed on the viscosity front is now 
> there is much less change (particularly with synthetic...) from cold 
> to hot.  But the measurement system essentially takes care of that.  
> The viscosities at the two temps where the two numbers (10W50, for 
> example) are measured is same now as 50 years ago.
> But at temps either much below or much above those measurement points, 
> newer oil is a lot better.  Plus, older oils would burn up at temps 
> where synthetics are just hitting their stride.......
>
> One huge advantage to synthetics (and to some extent the 'hybrid'
> blends) is that "viscosity improvers" were necessary in dino oil to 
> achieve a multi weight rating.  Synthetics just naturally have the 
> characteristics of a multi weight.  For example, a 10W synthetic has 
> the same viscosity as 10W dino at room temperature, but when hot the 
> synthetic doesn't thin as much.  So the 10W synthetic naturally 
> behaves like a 50W (or whatever - example made up!) dino oil at 
> elevated temps because the hot 50W dino has thinned excessively.
>
> Hans.
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