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

Re: All about oil????	<– Date –> <– Thread –>
From: LarryT (l02turnercomcast.net)
Date: Tue, 25 Mar 2008 18:10:13 -0700 (PDT)

Hans wrote << measurement temp is 212deg F - why it's related to water boiling temp

is anyone's guess>>

Hi Hans, One of the tests performed in our Oil Analysis is the viscosity of the sample measured at 100C. As you say, it may a semi-arbitrary number but I believe a number around the upper end of the operating spectrum needed to be used - so we know what the viscosity will be when our engines are at their hottest (hopefully). We probably converted to 212F just because it's more familiar.

If interested, you can look at some tests performed on new oil straight from the bottle - there are several tests like this - 4 IIRC - with different types of oil. You can compare what the engines different weights are at 100C to get an idea of what the oils do as they age. The number of miles on each sample is also shown if provided by the customer.

The test results can be found at http://members.rennlist.com/oil which is always in my sig lines.

Larry T (66 MGB, 74 911, 91 300D)
www.youroil.net for Oil Analysis and Weber Parts
Test Results http://members.rennlist.com/oil
PORSCHE POSTERS!  youroil.net
800-583-8601
Weber Carb Info http://members.rennlist.com/webercarbs

----- Original Message ----- From: "Hans E. Hansen" <FList [at] hanshansen.org> To: "Larry Turner" <l02turner [at] comcast.net> Cc: "The FerrariList" <ferrari [at] ferrarilist.com> Sent: Tuesday, March 25, 2008 8:50 PM 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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