Forums Migration

Please read this thread

Recent Topics
High Flow Thermostats
by Nick1994 - 07/12/20 02:51 AM
Hy-per Lube ZDDP Supplement 6pk $13.00
by alchargo - 07/11/20 10:38 PM
97 Civic HX valve cover pics
by CARJ - 07/11/20 10:22 PM
Time to ditch Speedplays
by UG_Passat - 07/11/20 10:03 PM
Dale L Nuzum
by Dalenuzum - 07/11/20 10:02 PM
*BANG* (Garage Door Spring)
by ctechbob - 07/11/20 09:40 PM
TPMS Sensors
by 92saturnsl2 - 07/11/20 09:16 PM
Chevron Delo 400 XSP 5W-30 XSP
by Gene K - 07/11/20 08:48 PM
LED retrofit for recessed can lights
by Donald - 07/11/20 07:08 PM
PP HM 5W-20 $15 at Wally
by Jackson_Slugger - 07/11/20 07:03 PM
Defeated by roll pin
by bcossa2001 - 07/11/20 06:56 PM
Dexron VI in place of Mercon LV?
by BigLee - 07/11/20 06:50 PM
89 c4 oil
by dogememe - 07/11/20 06:17 PM
Noticed the Titanium info.
by Farnsworth - 07/11/20 06:16 PM
FebiBilstein Parts
by willbur - 07/11/20 06:03 PM
Life goes on
by 53' Stude - 07/11/20 06:02 PM
Lubegard in a GM transfer case?
by BlakeB - 07/11/20 05:21 PM
Is MSO2 Liquid Moly OK in DIG NA engines
by JimPghPA - 07/11/20 03:10 PM
Rider Magazine Question
by Smoky14 - 07/11/20 02:38 PM
Newest Members
cadillactech, ILoveOil111, quantalume, SUmeme22, DaveCaddell
71910 Registered Users
Who's Online Now
25 registered members (2009Edge, bismic1, Char Baby, ctechbob, Ausfahrt, 4 invisible), 624 guests, and 28 spiders.
Key: Admin, Global Mod, Mod
Forum Statistics
Forums67
Topics307,747
Posts5,316,944
Members71,910
Most Online4,538
Jan 20th, 2020
Donate to BITOG
Print Thread
Hop To
Friction or hydrodynamic lubrication #5453546 06/14/20 08:48 AM
Joined: May 2018
Posts: 1,797
K
ka9mnx Offline OP
OP Offline
K
Joined: May 2018
Posts: 1,797
I have been visiting this topic in my head for many years.

If I could run an engine in a hypothetical lab condition eliminating outside influences such as road conditions, terrain, humidity, temperature, wind, drag, etc. With these parameters set, I record fuel economy over a range of engine loads and speeds with oil "x". Now, with oil x completely flushed, I now run oil "y". Oil y shows an average MPG better than oil x.

Would the increase of average MPG of oil y be due to the oils reduction of mechanical friction in the engine or the reduced hydrodynamic drag of the oil? Or would both contribute.

Facts please. No speculation please. References to publications would be extremely helpful.


2005 Ranger 3.0 - SuperTech Syn 0w-20/Motorcraft
2000 4Runner 3.4 - SuperTech Syn 5w-30/Toyota
1997 B2500 Van 3.9 - M1 HM 10w-30/Mopar
1993 F150 4.9 - SuperTech Syn 5w-30/Motorcraft
Re: Friction or hydrodynamic lubrication [Re: ka9mnx] #5453596 06/14/20 09:42 AM
Joined: Apr 2020
Posts: 557
ABN_CBT_ENGR Offline
Offline
Joined: Apr 2020
Posts: 557
Originally Posted by ka9mnx
I have been visiting this topic in my head for many years.

If I could run an engine in a hypothetical lab condition eliminating outside influences such as road conditions, terrain, humidity, temperature, wind, drag, etc.

Oil y shows an average MPG better than oil x.

Would the increase of average MPG of oil y be due to the oils reduction of mechanical friction in the engine or the reduced hydrodynamic drag of the oil? Or would both contribute.

Facts please. No speculation please. References to publications would be extremely helpful.


I do this a good bit so I'll address it and the authority is the conservation of energy

By your standards where all parameters were 100% identical and equal at all ranges

If a difference occurred from the oil only- then the only mode could be a relative property that only the oil directly influences.

That would be friction from 2 body contact created the "delta"

( assuming no particulate presence to grind and change clearance or finish since this is hypothetical) That can only come from

Dimensional increase from a change in heat removal ( thermal growth)

Increase in film strength

Here's the potential paradox

If nothing else changed- it would not be possible for the other oil to achieve either because the potential energy to allow for those alterations would not exist because it was never introduced. ( if no operating parameter changed then it would not present a circumstance to take advantage of any other oil property even if it was present)

So even if the simple concept of cause/effect is employed and oil "X" achieves a performance value of "1"- oil "Y" could not exceed "1" ( it could be argued that it could achieve less than 1) unless something else changed which was not allowed due to the constraints you imposed in your model.

Re: Friction or hydrodynamic lubrication [Re: ABN_CBT_ENGR] #5453616 06/14/20 10:07 AM
Joined: May 2018
Posts: 1,797
K
ka9mnx Offline OP
OP Offline
K
Joined: May 2018
Posts: 1,797
Excellent! Thank you...


2005 Ranger 3.0 - SuperTech Syn 0w-20/Motorcraft
2000 4Runner 3.4 - SuperTech Syn 5w-30/Toyota
1997 B2500 Van 3.9 - M1 HM 10w-30/Mopar
1993 F150 4.9 - SuperTech Syn 5w-30/Motorcraft
Re: Friction or hydrodynamic lubrication [Re: ka9mnx] #5453639 06/14/20 10:30 AM
Joined: Dec 2010
Posts: 5,134
G
Gokhan Offline
Offline
G
Joined: Dec 2010
Posts: 5,134


2020 Toyota Prius Prime XLE plug-in hybrid, 2ZR-FXE engine, ~ 65 mpg on regular gasoline, ~ 5,000 mi
TGMO 0W-16 SN/RC Japan
OEM spin-on oil filter Japan
Re: Friction or hydrodynamic lubrication [Re: ka9mnx] #5454116 06/15/20 01:03 AM
Joined: Jul 2010
Posts: 24,014
Z
ZeeOSix Offline
Offline
Z
Joined: Jul 2010
Posts: 24,014
Originally Posted by ka9mnx
Would the increase of average MPG of oil y be due to the oils reduction of mechanical friction in the engine or the reduced hydrodynamic drag of the oil? Or would both contribute.


Both would contribute if oil x and y were different viscosity because of the difference in oil shear drag between parts - that's the main reason that xW-20 is recommended by most manufacturers over xW-30 to get a little more gas mileage for CAFE credits.

And there may be more friction due to more metal-to-metal contact (surface asperities contact, mainly in the boundary and mixed lubrication realms) if one oil was much thinner than the other, and the level of friction when that happens would depend on the anti-friction additives in the oil.

In full hydrodynamic lubrication in journal bearings, it's mainly the oil shear drag due to viscosity that plays the main role, but if the viscosity becomes too thin then the MOFT can become too small to prevent metal-to-metal contact.

Re: Friction or hydrodynamic lubrication [Re: ZeeOSix] #5454176 06/15/20 06:46 AM
Joined: May 2018
Posts: 1,797
K
ka9mnx Offline OP
OP Offline
K
Joined: May 2018
Posts: 1,797
Thanks and that is exactly how I envision what's happening. I recently changed my Ranger from 5w-30 to 0w-20. I wasn't expecting much change but the engine feels like it revs easier before warm up ([email protected]). Verdict is still out on MPG but I'm expecting to see a slight up tick in MPG (modern additives) after what I'm experiencing now pre warm up.


2005 Ranger 3.0 - SuperTech Syn 0w-20/Motorcraft
2000 4Runner 3.4 - SuperTech Syn 5w-30/Toyota
1997 B2500 Van 3.9 - M1 HM 10w-30/Mopar
1993 F150 4.9 - SuperTech Syn 5w-30/Motorcraft
Previous Thread
Index
Next Thread

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