Recent Topics
Michelin Premier LTX Different Tread
by chuck wood - 01/20/20 08:49 AM
Best ear plugs for concerts,clubs?
by aquariuscsm - 01/20/20 07:47 AM
Oil ideas for 2 v6 fords and more
by kessellrun - 01/20/20 06:50 AM
Chery A520 2.0 L Transmisstion Oil
by Omar_Eltahan - 01/20/20 02:38 AM
castrol 5w30 c3 for an LS?
by neo3 - 01/19/20 11:32 PM
Windows 10 Upgrade Guide
by OVERKILL - 01/19/20 09:59 PM
FCA and Foxconn partner on EV's
by OVERKILL - 01/19/20 08:55 PM
IIHS Crash pics of Full Size Trucks
by kstanf150 - 01/19/20 08:15 PM
Are Engine Splash Guards Really Needed?
by Mr_Luke - 01/19/20 08:14 PM
supertec cartridge filters
by super20dan - 01/19/20 06:17 PM
More Valvoline on rollback at WM
by jayjr1105 - 01/19/20 06:13 PM
Crossed poles on jumper cables
by 3Aone - 01/19/20 05:33 PM
Napa Gold 7060 7.5K miles
by KenshinHimura - 01/19/20 05:09 PM
Can you move a car with the starter?
by atikovi - 01/19/20 04:49 PM
Leaf spring advice.
by mpack88 - 01/19/20 02:19 PM
Newest Members
Bobjr94, GarageKings, JohnnyD1980, Harry_Seaward, MrH1325
70486 Registered Users
Who's Online Now
95 registered members (aquariuscsm, atikovi, angeloc, Alex_V, 2004tdigls, 25ring, 14 invisible), 2,216 guests, and 38 spiders.
Key: Admin, Global Mod, Mod
Forum Statistics
Forums67
Topics300,340
Posts5,173,712
Members70,486
Most Online3,825
Jan 19th, 2020
Donate to BITOG
Print Thread
Hop To
Page 1 of 3 1 2 3
Synthetic oil worse for cooling? #5313131 01/04/20 01:01 PM
Joined: May 2014
Posts: 542
S
slybunda Offline OP
OP Offline
S
Joined: May 2014
Posts: 542
Taken from here:
https://www.vwheritage.com/lowdown-oil

Quote
Synthetic oils typically have quite different heat transfer characteristics to mineral oils. On modern water-cooled units this is not a problem, but on the air-cooled unit where a significant part of the overall engine cooling comes through oil cooling, the use of synthetic oils can cause problems. As the amount of heat dissipated by the oil is reduced, the engine runs hotter.


I thought it was the opposite and synthetic oil is better for cooler running due to reduced friction?


1995 Ford Fiesta 1.6i 16v Si
2000 Toyota Celica 1.8 VVTL-i
2007 Toyota Aygo+ 1.0i
Re: Synthetic oil worse for cooling? [Re: slybunda] #5313139 01/04/20 01:08 PM
Joined: Nov 2008
Posts: 15,202
S
supton Online Content
Online Content
S
Joined: Nov 2008
Posts: 15,202
Originally Posted by slybunda
Taken from here:
https://www.vwheritage.com/lowdown-oil

Quote
Synthetic oils typically have quite different heat transfer characteristics to mineral oils. On modern water-cooled units this is not a problem, but on the air-cooled unit where a significant part of the overall engine cooling comes through oil cooling, the use of synthetic oils can cause problems. As the amount of heat dissipated by the oil is reduced, the engine runs hotter.


I thought it was the opposite and synthetic oil is better for cooler running due to reduced friction?

I think you have two effects there--reduced friction would lead to cooler engine & oil. But that is separate from the heat transfer capability of the oil, or in other words, the ability of the oil to absorb (and then release) heat. Two different things.

I have not heard of this before, heat transfer being different. I wouldn't think it would be much different though.


2011 Toyota Camry, base, 2.5L/6MT, 200k, hers
2010 Toyota Tundra DC, 4.6L/6AT, 157k, ours
1999 Toyota Camry LE, 2.2L/4AT, 220k, his
Re: Synthetic oil worse for cooling? [Re: supton] #5313180 01/04/20 01:59 PM
Joined: May 2017
Posts: 12
E
Earls1st Offline
Offline
E
Joined: May 2017
Posts: 12
I first (and maybe never since then until now) heard this from a Conklin distributor 25-35 years ago. I think the rationale was small, uniform molecule size in synthetics vs. varied, larger size molecules in dino oil. Still don't know if it has any functional significance or how you'd determine than, but I suppose there is a way to quantify heat transfer through a material and its interaction at material interfaces.

As an aside, how come no one talks about UOAs using Conklin products - looks like the they're still in business, if the existence of a website is an indication.

Re: Synthetic oil worse for cooling? [Re: slybunda] #5313244 01/04/20 03:07 PM
Joined: Nov 2006
Posts: 22,768
T
Trav Offline
Offline
T
Joined: Nov 2006
Posts: 22,768
I have a small Honda CB Seven Fifty for around town (not the stone old CB750), it is air cooled 74 HP with a small oil cooler and a mechanical screw in oil temp gauge. No noticeable difference between Dino and synthetics. I am not buying it.


ASE L1, Master. Deutsch Meisterbrief.
Re: Synthetic oil worse for cooling? [Re: slybunda] #5313276 01/04/20 03:59 PM
Joined: Aug 2003
Posts: 888
N
nicholas Offline
Offline
N
Joined: Aug 2003
Posts: 888
This is total BS.
Look at Redline and other ester syn oils.


2019 2.0T Santa Fe
2010 3.5 Santa Fe
Re: Synthetic oil worse for cooling? [Re: slybunda] #5313296 01/04/20 04:26 PM
Joined: May 2019
Posts: 3,392
M
Mad_Hatter Offline
Offline
M
Joined: May 2019
Posts: 3,392
This is way outside my wheelhouse but what the heck, I'll take a stab at this...Wouldn't density be a factor in determining thermal capacity? And isn't mineral typically denser than a synthetic (look at a PDS), so it stands to reason mineral would be a "better" heat transfer medium, no? But it's got downsides right? Like not very thermally stable at high temps, which is where synthetics excel. I know minerals are used a lot in air cooled systems like transformers and such..

Last edited by Mad_Hatter; 01/04/20 04:29 PM.
Re: Synthetic oil worse for cooling? [Re: slybunda] #5313383 01/04/20 06:10 PM
Joined: Apr 2009
Posts: 690
W
walterjay Offline
Offline
W
Joined: Apr 2009
Posts: 690
Several years ago Briggs and Stratton demonstrated that there was a 10 degree reduction in temperature when dino was drained out and run with Synthetic.
I can personally attest to the cooling effect of syn. I bought an air cooled John Deere riding mower with a 25 horsepower Kohler engine. The thing ran so hot that when it was shut down it would knock and run on for a good bit. To get it to keep from running on I had to cool it down for at least three minutes before shutting it off. And the thing radiated heat from the engine like a stove. I drained out the factory fill and filled with Mobil 1 5-30. The thing no longer ran on and I could shut it down a few seconds after mowing without run on. There was also noticeably less radiant heat coming off the engine.
I told the story to an old mechanic and he said this was BS. But I saw and experienced it and have run nothing but syn in everything ever since.

Re: Synthetic oil worse for cooling? [Re: slybunda] #5313388 01/04/20 06:25 PM
Joined: Apr 2018
Posts: 583
T
talest Offline
Offline
T
Joined: Apr 2018
Posts: 583
Same way people try to say that you can't use synthetic oil in a Rotary (RX-7, RX-8) engine, then consider themselves to have been knowledgeable...

Re: Synthetic oil worse for cooling? [Re: slybunda] #5313392 01/04/20 06:32 PM
Joined: Aug 2018
Posts: 1,006
RDY4WAR Offline
Offline
Joined: Aug 2018
Posts: 1,006
That is some weapons grade bullspit.


"He who is without oil, shall throw the first rod." - Compressions 9:1
Re: Synthetic oil worse for cooling? [Re: slybunda] #5313393 01/04/20 06:33 PM
Joined: Jun 2019
Posts: 230
T
tblt44 Offline
Offline
T
Joined: Jun 2019
Posts: 230
Less friction = less heat but I think most of what will heat your engine is the firing of the cylinders not friction no matter what oil you use.
If there was so much friction to cause the engine to heat to 190 deg within a few minutes our engines wouldn't last.
J.M.O.


2003 Avalanche Z71 5.3
2006 Tahoe 5.3
1989 Yamaha moto 4 250
2004 Key Largo w/70 Yamaha 2 stroke
Re: Synthetic oil worse for cooling? [Re: slybunda] #5313395 01/04/20 06:34 PM
Joined: Jun 2019
Posts: 230
T
tblt44 Offline
Offline
T
Joined: Jun 2019
Posts: 230
Less friction = less heat but I think most of what will heat your engine is the firing of the cylinders not friction no matter what oil you use.
If there was so much friction to cause the engine to heat to 190 deg within a few minutes our engines wouldn't last.
J.M.O.


2003 Avalanche Z71 5.3
2006 Tahoe 5.3
1989 Yamaha moto 4 250
2004 Key Largo w/70 Yamaha 2 stroke
Re: Synthetic oil worse for cooling? [Re: Mad_Hatter] #5313400 01/04/20 06:41 PM
Joined: Mar 2016
Posts: 2,611
C
CR94 Offline
Offline
C
Joined: Mar 2016
Posts: 2,611
Originally Posted by Mad_Hatter
This is way outside my wheelhouse but what the heck, I'll take a stab at this...Wouldn't density be a factor in determining thermal capacity? And isn't mineral typically denser than a synthetic (look at a PDS),..
Partly right. Ability of a fluid to transfer heat depends on its viscosity, density, specific heat, and thermal conductivity.


2011 Toyota Prius now at 107K
1981 Mazda GLC (323) retired at 606K
1972 Subaru DL retired at 190K
1954 Chevrolet retired at 121K
Re: Synthetic oil worse for cooling? [Re: slybunda] #5313413 01/04/20 07:13 PM
Joined: Jun 2002
Posts: 20,759
MolaKule Offline
Global Moderator
Offline
Global Moderator
Joined: Jun 2002
Posts: 20,759
You have to split off temperature rise due to friction and the transfer of thermal energy due to the fluids alone.

Originally Posted by MolaKule
Here is some comparative information I derived using the Heat Convection and Conduction formulas:

NOTE: This was for pure mineral oil verses pure PAO synthetic both 10.5 [email protected]

Convective Calc:

H = F.rho.c(To-Ti),
where H is heat energy in Joules, F is volume flow in cubic meters/s,
c is heat capacity in Joules/kg.C, and temps in C. The c for synthetic oil is 2000 J/kg.C and c for dino is 1780 J/kg.C. I assumed a flow rate was 1/4 liter per second, To is temp out of a journal bearing = 100 C, and Ti was oil temp into bearing = 80C, representing a temp rise of 20C, which is a rule of thumb.

Hs = convective energy transfer in Joules for synthetic = 10.65 J
Hd = convective energy transfer in Joules for dino (mineral oil) = 9.3 J.

Therefore, pure synthetic oil is 13% more efficient at convective heat transfer.

The "rho" factor (oil convection heat transfer) is the oil's density, measured in kg/cubic meters, and since both oils were so close in density, I used 1.065 kg/cubic meter.



Using the Heat Conduction formula:

H = kA(To-Ti/L),

where H is heat Power in W.m, k is heat conduction coefficient in W/meter-squared/C, and temps in C. The k for synthetic oil is 0.16 and k for dino is 0.128, To is temp out of a journal bearing = 100 C, and Ti was oil temp into bearing = 80C, representing a temp rise of 20C, which is a rule of thumb. L is the thickness of the oil film which is on the order of 1um at high loads. A is area of film assumed to be a patch of area of 1 mm squared.

Hs = conductive heat transfer of synthetic oil in W = 3200 W,
Hd = conductive heat transfer of dino (mineral oil) in W = 2560 W.

Therefore, pure synthetic oil is 20% more efficient at conductive heat transfer than mineral oil.

The same film thickness for both dino's and synth's were used for the calculations.

These are heat transfer formulas from thermodynamics and the constants I used for "c" and "k" were from Michael J. Neal's, The Handbook of Tribiology.

(From BITOG 07/02)

Last edited by MolaKule; 01/04/20 07:21 PM.

Charlie Eppes: "What do you think we should do now?"
Don Eppes: "The same thing when I was in school and I didn't know the answer – fake it." From NUMB3RS
Re: Synthetic oil worse for cooling? [Re: slybunda] #5313422 01/04/20 07:26 PM
Joined: Apr 2009
Posts: 690
W
walterjay Offline
Offline
W
Joined: Apr 2009
Posts: 690
Thank you for clearing that up MolaKule!

Re: Synthetic oil worse for cooling? [Re: slybunda] #5313439 01/04/20 07:44 PM
Joined: Sep 2004
Posts: 8,614
A
andyd Offline
Offline
A
Joined: Sep 2004
Posts: 8,614
Yes Thank you. When I read thread. I felt that synth would conduct heat better because its molecules are identical.. any basis in fact? TIA grin2


'16 Camry LE STP synth 0w20 and STP filter. the Fridge

1994 Ranger ,the Rat, 5w30 dino, STP filter

'16 Camry SE, Valvoline HM 0w20 and OEM filter
Thick oil is better grin2
Page 1 of 3 1 2 3
Previous Thread
Index
Next Thread

BOB IS THE OIL GUY® Powered by UBB.threads™