Recent Topics
many ACEA a5/b5 and a3/b4 only api SL
by shDK
11/24/14 06:23 AM
New Plugs are Powdery Black. w/PIC. Diagnosis?
by Turk
11/24/14 05:14 AM
Looking for new oil/oil filter combo..
by radtech91
11/23/14 11:13 PM
Best atf for volvo 4t65ev/gt
by pjc360
11/23/14 10:43 PM
A New Cert mark for ILSAC GF-6B?
by wemay
11/23/14 10:24 PM
APPLES
by JHZR2
11/23/14 09:42 PM
where is the best deal on Dexron VI ?
by LScowboy
11/23/14 09:33 PM
Engines designed around oil?
by Throt
11/23/14 09:30 PM
Battery sprung a leak!
by JHZR2
11/23/14 09:30 PM
DVR for TV
by Jimkobb
11/23/14 09:10 PM
Newbie question on power bleeders for brake
by volodymyr
11/23/14 06:54 PM
Tire size variations
by GerGa
11/23/14 05:04 PM
Newest Members
kinder, SamBruin7, splatt, Lars65inc, dothedrew1202
51984 Registered Users
Who's Online
72 registered (A_Harman, asand1, Asterix, AandPDan, 3311, 9 invisible), 1232 Guests and 143 Spiders online.
Key: Admin, Global Mod, Mod
Forum Stats
51984 Members
66 Forums
222542 Topics
3522412 Posts

Max Online: 2862 @ 07/07/14 03:10 PM
Donate to BITOG
Topic Options
#2479716 - 01/01/12 09:06 PM Oil Viscosity vs. Oil Pressure
blackdiamond Offline


Registered: 03/05/07
Posts: 618
Loc: Western Washington
What connection is there between oil viscosity and oil pressure? The engine in question is a 20r/22r hybrid that is driven like a race car. The owner indicated that 20w-50 wasn't cutting the mustard and the reason was that it wouldn't hold oil pressure at high rpm. At some point it seems that the oil pump wouldn't be able to keep up with the higher viscosity.

Any thoughts?
_________________________
1989 Toyota 4Runner / 5w-30 Pennzoil Platinum
2004 Toyota Sequoia / 5w-30 Mobile 1 EP
2008 Honda Civic / Unknown

Top
#2479721 - 01/01/12 09:11 PM Re: Oil Viscosity vs. Oil Pressure [Re: blackdiamond]
GMorg Offline


Registered: 01/29/06
Posts: 2349
Loc: Mizzou-land
Exactly what does "hold oil pressure" mean in this context? Are you saying that oil pressure would not continue to rise or that oil pressure would actually drop at high RPM?

Top
#2479746 - 01/01/12 09:37 PM Re: Oil Viscosity vs. Oil Pressure [Re: blackdiamond]
AITG Offline


Registered: 12/22/06
Posts: 339
Loc: USA
On a theoretical level, pressure is the result of resistance to flow. Thinner fluids flow more easily, therefore less pressure is required to move them. Larger clearances result in less resistance, therefore less pressure will be required to move a given volume in a given time.

Practically, thicker fluids may result in more pressure but less flow. Worn components result in lower pressures but increased flow.

AFA the racer is concerned: I have no idea what he was getting at - sorry.

Top
#2479760 - 01/01/12 09:50 PM Re: Oil Viscosity vs. Oil Pressure [Re: blackdiamond]
sm00thpapa Offline


Registered: 07/09/11
Posts: 867
Loc: Spring Hill, FL
_________________________
14 Elantra Factory fluids and filter
09 FZ6R, K&N 204, SRT 15W-40
04 Ascender, P1, Napa SYN 5W-30
96 Cavalier, PC, Maxlife 10W-30

Top
#2479778 - 01/01/12 10:09 PM Re: Oil Viscosity vs. Oil Pressure [Re: sm00thpapa]
ltslimjim Offline


Registered: 08/06/10
Posts: 5143
Loc: PL&F
Originally Posted By: sm00thpapa




thumbsup
_________________________
1992 Civic VX 275k+
HG replaced, waiting to sample

Top
#2479963 - 01/02/12 07:08 AM Re: Oil Viscosity vs. Oil Pressure [Re: blackdiamond]
AEHaas Offline


Registered: 01/09/05
Posts: 1312
Loc: Sarasota, Florida
One reason may be that the oil pump bypass pressure is set too low for your application / oil grade combination.

The later chapters below may illustrate the issue:


http://ferrarichat.com/forum/faq.php?faq=new_faq_item#faq_haas_articles

Original (but edited by others) version:

http://www.bobistheoilguy.com/motor-oil-101/

aehaas
_________________________
Machine Guns.
Sarasota Home Inspections.

Top
#2480335 - 01/02/12 02:45 PM Re: Oil Viscosity vs. Oil Pressure [Re: blackdiamond]
mechtech2 Offline


Registered: 09/05/06
Posts: 19479
Loc: Chicago Area
It could be too much heat, which can require a thicker oil to keep the pressure up.
But if an engine needs more than a 50 [which you have], it is extreme, for sure.

Top
#2480555 - 01/02/12 05:52 PM Re: Oil Viscosity vs. Oil Pressure [Re: blackdiamond]
aquariuscsm Offline


Registered: 12/30/06
Posts: 10005
Loc: South Texas,USA
If you need a thicker than 20W50,there`s always a mono grade 50 or 60.
_________________________
1996 Nissan 300ZX 5-speed,Arctic Pearl(#175 of 300)
Syntec 10W40/Fram Ultra
Amsoil MTG(tranny)
Amsoil 80W90 GL5(rear diff)
Mobil 1 ATF
Redline Water Wetter

Top
#2481135 - 01/03/12 10:04 AM Re: Oil Viscosity vs. Oil Pressure [Re: blackdiamond]
A_Harman Online   content


Registered: 10/01/10
Posts: 4370
Loc: Michigan
Originally Posted By: blackdiamond
What connection is there between oil viscosity and oil pressure? The engine in question is a 20r/22r hybrid that is driven like a race car. The owner indicated that 20w-50 wasn't cutting the mustard and the reason was that it wouldn't hold oil pressure at high rpm. At some point it seems that the oil pump wouldn't be able to keep up with the higher viscosity.

Any thoughts?


Maybe the 20w50 is TOO thick. The higher viscosity oil will drain back to the pan more slowly than a 5w30, making it more likely that the pickup will starve for oil during hard acceleration or cornering. How much oil pressure is it maintaining at high rpm? Under what driving conditions is the oil pressure dropping?
_________________________
1985 Z51 Corvette track car
2002 Camaro Z28 LS1/6-speed
2001 Dodge Ram 2500 diesel
1972 GMC 1500 shortbed project truck

Top