[E-Type] Restatement on viscosity and engine temp

E-Type
1

There was not a big response to my previous mention about
what I perceive as a big reduction in engine temp due to
the use of a lower viscosity oil…I changed from 10-40 to
5-30 and see that my engine temp does not get above 70 for
about 15 min later at idle(70f ambient)…the fan does not
even come on for 18 min…i think this is significant for
those with overheating engines–
Pjwilletts 62 ots, 60 Bugeye sprite
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2

In reply to a message from PeteWilletts sent Wed 11 Nov 2015:

Last time you said you changed to ‘10-30’[sic]. You didn’t
say what from. You said the temp never got above 70F but
didn’t say what it used to do. It’s kinda hard to draw
meaningful conclusions from incomplete data unless you’re
a politician.

Maybe writing that you went out for 20 minutes on a mild
day and nothing bad happened lacks a bit of sparkle.
People are so jaded these days and the news is so hyped up
that folks could think a good news story like yours is up
there with watching paint dry and a few notches below the
Texas Chainsaw Massacre in the excitement stakes. OK, I’ve
never watched it, but I don’t let facts get in the way of
a good theory.

Now comes the hard part. The scientist in you has already
realised you’ll need to go out for 21 minutes, then 22, 23
and 24 etc, letting that big old iron block cool right
down between runs. Better hope the ambient doesn’t soar to
63-64F or plummet to 60-61F. The reward will be finding
the Holy Grail and as you say people with ‘overheating’
engines’, however defined, will reach for the sump plug
instead of the radiator cap. ‘Significant’ is too small a
word - it needs at least two more letters.

Enjor the car. Tried starting mine yesterday and the
battery was low :frowning:

Pete–
The original message included these comments:

There was not a big response to my previous mention about
what I perceive as a big reduction in engine temp due to
the use of a lower viscosity oil…I changed from 10-40 to
even come on for 18 min…i think this is significant for
those with overheating engines

–
1E75339 66 D, 1R27190 70 FHC, 79 S2 XJ12L
Gaithersburg, Maryland, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

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3

In reply to a message from PeterCrespin sent Thu 12 Nov 2015:

Maybe your electrolyte is too viscous ??–
The original message included these comments:

Enjor the car. Tried starting mine yesterday and the
battery was low :frowning:
Pete
The original message included these comments:

There was not a big response to my previous mention about
what I perceive as a big reduction in engine temp due to
the use of a lower viscosity oil…I changed from 10-40 to
even come on for 18 min…i think this is significant for
those with overheating engines
1E75339 66 D, 1R27190 70 FHC, 79 S2 XJ12L
Gaithersburg, Maryland, United States

–
Keith.P. Series2 Roadster
exmouth, United Kingdom
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4

In reply to a message from PeteWilletts sent Wed 11 Nov 2015:

PeteW,

That has not been my experience over 41 years of use. I gu
guess your results were kind of a fluke?

Jerry–
The original message included these comments:

what I perceive as a big reduction in engine temp due to
the use of a lower viscosity oil…I changed from 10-40 to
5-30 and see that my engine temp does not get above 70 for
about 15 min later at idle(70f ambient)…the fan does not
even come on for 18 min…i think this is significant for
those with overheating engines

–
Jerry Mouton '64 FHC 889791 ‘MIK Jaguar’
Palo Alto, California, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

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5

Good point Pete…
But also…
There is no reason a well fretted Jag engine should overheat. I’ve been on a Phoenix freeway in stop-and-go traffic on a hot day with the A/C on in my sII and it worked hard but didn’t overheat. That, by any standards, was an extreme test. Oil viscosity is irrelevant in that extremem case.
Under similar circumstances, the sI with single blade windmill fan does have an excuse to overheat.
LLoyd----- Original Message -----

Last time you said you changed to ‘10-30’[sic]. You didn’t
say what from. You said the temp never got above 70F but
didn’t say what it used to do. It’s kinda hard to draw
meaningful conclusions from incomplete data unless you’re
a politician.

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6

I agree with Jerry. There is a difference, of course, but I don’t think it is actually measurable. Seems to me that if your car sat and idled in the garage for 8 hours and fourteen minutes, the fan might be on for seventy two seconds longer.
LLoyd@PFFFFFT.com (as Bill the cat would say)----- Original Message -----
In reply to a message from PeteWilletts sent Wed 11 Nov 2015:

That has not been my experience over 41 years of use. I gu
guess your results were kind of a fluke?

Jerry

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7

In reply to a message from PeterCrespin sent Thu 12 Nov 2015:

Morning,
I think that Pete makes a good point about oil acting as a
coolant and a lower viscosity oil is going have increased flow
helping to lower the heat in a given part of the engine.
The other thing that has confused me is that I always thought
that the higher the pressure the better off one was, my
reading would suggest that flow is the critical issue not
pressure (of course one has to have pressure to flow but at a
certain point there are diminishing returns).

Here is an article that I found on the Ferrari chat site that
I though was well written explanation of viscosity and backs
up Jerry’s and Pete’s rational quite well.

Oh, one last thing Peter ©, your engine will crank at a
higher speed with a lower viscosity oil :wink:

http://tinyurl.com/pttjvzz

Cheers,
Lynn–
The original message included these comments:

Enjor the car. Tried starting mine yesterday and the
battery was low :frowning:
Pete

–
Lynn G.
68/85 ots, 73 2+2, Boise, Id., United States
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8

In reply to a message from L.Lynn sent Thu 12 Nov 2015:

Come on, Lynn, this guy is an MD, what would he know? ; -)

Jerry

PS, I like that article too.–
Jerry Mouton '64 FHC 889791 ‘MIK Jaguar’
Palo Alto, California, United States
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9

In reply to a message from L.Lynn sent Thu 12 Nov 2015:

Excellent point. Ask yourself what cools the underside of
the piston.
And back in 1978, Scientific American magazine had an
article about the hydrodynamic effects of journal bearings
that showed that a shaft rotating in its journal will create
and maintain its own fluid film. Remember, a Model T Ford
didn’t even have an oil pump!–
The original message included these comments:

I think that Pete makes a good point about oil acting as a
coolant and a lower viscosity oil is going have increased flow
helping to lower the heat in a given part of the engine.
The other thing that has confused me is that I always thought
that the higher the pressure the better off one was, my
reading would suggest that flow is the critical issue not
pressure (of course one has to have pressure to flow but at a
certain point there are diminishing returns).
Here is an article that I found on the Ferrari chat site that

–
Pete Peterson 70E(193K) XJ40s(88-270K,89-97K, 94-122K)
Severna Park, Maryland, United States
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10

Pete,
Hopefully someone with thermodynamics experience will speak up however
from a layman’s view (mine) I don’t see how a noticeable temp
difference could happen. The oil is a coolant, more or less of it
would make a difference but the same amount at a slightly different
viscosity shouldn’t. Splitting hairs lower viscosity would create
less friction in the engine but again do not think you would find that
detectable on the gauge or otter switches. Many years ago I switched
from 20W50 to 10W30, I was only looking for an oil pressure change but
no temp changes occurred and none were expected. MHO.
pauls

There was not a big response to my previous mention about
what I perceive as a big reduction in engine temp due to
the use of a lower viscosity oil…I changed from 10-40 to
5-30 and see that my engine temp does not get above 70 for
about 15 min later at idle(70f ambient)…the fan does not
even come on for 18 min…i think this is significant for
those with overheating engines
<<<<<<<<<<<<From: “PeteWilletts” pjwilletts@hotmail.com
Subject: [E-Type] Restatement on viscosity and engine temp

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11

I like the article too with one exception; he says use thinner oil if
your engine is running hot and for some valid reasons. IMO that’s no
solution however, unless there is something added to dissipate the
extra heat gathered by the oil. As in greater dissipation area or an
oil cooler which I suspect the F car has, not so with the XK motor.
pauls

Come on, Lynn, this guy is an MD, what would he know? ; -)

Jerry

PS, I like that article too.
<<<<<<<<<<<<From: “mouton” jerry@moutons.org
Subject: Re: [E-Type] Restatement on viscosity and engine temp

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12

In reply to a message from PeteWilletts sent Wed 11 Nov 2015:

Pete,

IME, it can significantly reduced the oil temp moving from
say 20W-50 TO ‘‘X’’ lower, but I have not seen a massive
move in coolant temp.

It does stand to reason that that lower oil temp also
takes down the coolant temp (or in theroy should), but
that of course requires an accurate oil temp gauge.

I had to change my oil prior to a trip and had only 20W-50
in the house / was in a rush (non E-Type or XK motored
car). And the temps were a good 15 degress© higher, as
was my blood pressure due to intently watching the oil
temp gauge move up.

As for Jaguar content, I suspect the V12 operates at
better overall temp with lower viscosity on board.

Just my two sense.

Jeff–
The original message included these comments:

the use of a lower viscosity oil…I changed from 10-40 to
5-30 and see that my engine temp does not get above 70 for
about 15 min later at idle(70f ambient)…the fan does not
even come on for 18 min…i think this is significant for
those with overheating engines

–
'53 VII, '57 140M OTS, '67 XKE OTS, '72 XKE OTS
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

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13

In reply to a message from J Schroeder sent Thu 12 Nov 2015:

The article Lynn referred to is worth reading. It has
changed my thinking about always wanting to have thick oil
and higher oil pressure.

Thanks for mentioning the article–
Dennis Vancouver Canada 69 Roadster
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

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14

In reply to a message from Dennismo sent Thu 12 Nov 2015:

Reading the article mentioned is what got me thinking about
viscosity and cooling vs lubrication…Very often people do
not appreciate the role that oil plays in cooling( one
reason the oil quantity is so great on these engines)…it
does not take much oil press to satisfy basic lubrication
needs but the big benefit of increased flow as a result of
lower viscosity is heat transfer… if the viscosity is
lower a greater quantity of fluid will move through the
system for a given pressure…thus increasing heat
transfer…or so it seems to me…–
The original message included these comments:

The article Lynn referred to is worth reading. It has
changed my thinking about always wanting to have thick oil
and higher oil pressure.

–
Pjwilletts 62 ots, 60 Bugeye sprite
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

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15

In reply to a message from PeteWilletts sent Thu 12 Nov 2015:

I found this at:
http://www.machinerylubrication.com/Read/29295/temperature-
affects-lubricants
It mentions that the higher viscosity oil’s resistance to
flow will cause the engine to run hotter.

‘‘Since oil with a lower viscosity and high potential shear
rate must still maintain a sufficient oil film, it is quite
apparent that as temperatures rise, the oil film may fail
and metal-to-metal contact may occur. If the oil’s
viscosity is too high with a low potential shear rate, the
internal resistance to flow will increase the temperature
dramatically, causing an overheated condition, which can
also cause a breakdown of the oil film and may cause
oxidation of the oil. Therefore, it is critical that oils
be selected by always taking the operating temperature of
the equipment into account.’’

Here:

http://www.oilspecifications.org/articles/what-are-the-
reasons-of-oil-consumption.php

the author says: �Higher viscosity means worse cold
temperature performance, slower oil circulation, higher oil
pressure, less heat transfer and � sometimes, if the oil
passages are thin � worse lubrication even on operating
temperature.–
The original message included these comments:

lower viscosity is heat transfer… if the viscosity is
lower a greater quantity of fluid will move through the
system for a given pressure…thus increasing heat
transfer…or so it seems to me…

–
John Walker, 1969 E-Type Coupe
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16

In reply to a message from John Walker sent Thu 12 Nov 2015:

Pete #1
Why not just ask yourself the fundamental question:- is the aount
of work being done by the engine any different? Unless you have
fundamentally changed the thermodynamics, I suspect that the amount
of work being done is much the same and the split between useful
work, extracted heat and what disappears down the tailpipe also
isn’t much different.

If the water temperature has dropped, then it simply suggests that
the heat extracted via oil circulation has incresed. Since you
never measured that first time around, then your analysis is
incomplete, rather than significant.

If you cleaned out the engine block, passages, radiator etc etc,
then that sort of change in the setup also has to be factored into
your analysis.

kind regards
Marek–
v12 E-type running MS3/3X sequential lpg and petrol
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17

In reply to a message from MarekH sent Fri 13 Nov 2015:

Careful, Marek.

You’re perilously close to calling me Pete Number Two and I
may resemble that remark! We don’t allow ad hominem
flushing on this forum :-)–
The original message included these comments:

Pete #1

–
1E75339 66 D, 1R27190 70 FHC, 79 S2 XJ12L
Gaithersburg, Maryland, United States
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18

In reply to a message from PeterCrespin sent Fri 13 Nov 2015:

Pete Petersen:

Aha, something I know something about!!!

Model t Fords!!! On, they did/do
have an oil pump of sorts!!!

The massive flywheel has ‘‘V’’ shaped
magnets bolted and secured to it.
‘‘secure’’, sorta. another story.
A series of coils is mounted behind.
Enough juice for lighting, ‘‘sorta’’ and
plenty for ignition. Til the magnets
loose their ‘‘pull’’!!

To the point: Those magnets lift oil
from the low part of the sump, dump
it into a trough. thence, a pipe carries
it forward and dumps it on the cam gear
at the engine’s front.

Worked fairly well on level ground.
But, on a sustained climb, oh, oh!!!

A popular after market p[ice was an
additional external pipe to move more
oil up front.

On one kid adventure, we drove Billy’s
T up a steep long grade from Alamogordo,
to Las Cruces, New Mexico. Billy was
super anal about oiling. So, we took
turns laying on the fender and adding
oil up to the engine front. Stopped
from time to time to replenish the can
from the petcock on the sump. Henry’s
way of checking oil level!! Two petcocks!!

And,a cute way to make an external pump.
Never got around to it…

High viscosity oil is a deterrent to easy
cranking in bitter cold…

In my army days, GI oil for every thing
was 30!!!

Carl–
Carl Hutchins 1983 Jaguar XJ6 with LT1 and 1994 Jeep Grand
Walnut Creek, California, United States
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19

In reply to a message from cadjag sent Fri 13 Nov 2015:

Carl:
Are you suggesting that the flywheel on a model T ran
inside the sump?
My recollection is that each Model T rod cap had a scoop
attached, which made the engine ‘‘splash lubed’’. The scoop
had to have the proper orientation or it wouldn’t scoop the
oil. The splash was violent enough to put oil everywhere it
was required. As long as you maintained proper oil level
in the sump, that is.
Come to think of it, that’s the same method Briggs and
Stratton and Tecumseh still use on their small engines.–
The original message included these comments:

The massive flywheel has ‘‘V’’ shaped
magnets bolted and secured to it.
‘‘secure’’, sorta. another story.
A series of coils is mounted behind.
Enough juice for lighting, ‘‘sorta’’ and
plenty for ignition. Til the magnets
loose their ‘‘pull’’!!
To the point: Those magnets lift oil
from the low part of the sump, dump
it into a trough. thence, a pipe carries
it forward and dumps it on the cam gear

–
Pete Peterson 70E(193K) XJ40s(88-270K,89-97K, 94-122K)
Severna Park, Maryland, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

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20

In reply to a message from Jaguarpete sent Fri 13 Nov 2015:

I think he is, Pete. Engine, flywheel and tranny all shared
the same long sump, and the same oil. Oil drain was under
the flywheel IIRC. Not sure how long this lasted.

Carl, were there points associated with the magneto or just
the vibrating ones on each spark coil?–
The original message included these comments:

Are you suggesting that the flywheel on a model T ran

inside the sump?

–
Bob Wilkinson, 73 XJ6
Saint Louis, MO, United States
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