Using 10w-40 due to low oil pressure? - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Grand Cherokee & Commander Forums > ZJ Grand Cherokee Forum > Using 10w-40 due to low oil pressure?

FS: 2007-2013 Jeep Wrangler "HALO" Angel Eye KitFS: Wranger BRIGHT License Plate LED! Just $3! Great valueSPARTAN LOCKERS are on sale BIG TIME at ROCKRIDGE 4WD!

Reply
Unread 12-17-2012, 09:46 AM   #1
streetzj
Registered User
1997 ZJ 
 
Join Date: Dec 2009
Location: minnesota
Posts: 317
Using 10w-40 due to low oil pressure?

I'm using 10w-40 to increase my low oil pressure, which is caused by bad bearings. It increased the pressure from 5 psi to 9 psi over 5w-30 when I changed the oil this summer. But now it's winter here in Minnesota -- which weight should I use?

It seems to me that it's a matter of the least worst -- when the engine is warmed up after about 20 minutes, the 5w-30 will cause the pressure to go back down to 5 psi, which is bad. But when I start it in the cold, the 10w-40 is too thick to reach the top right away, which is bad.

Either way, the oil won't reach the top at some point. And important note -- the pressure is only low at idle and is fine at cruising speed, and increases to normal from low pressure when I accelerate.

streetzj is offline   Reply With Quote
Unread 12-17-2012, 09:51 AM   #2
JohnnyZJ
Web Wheeler
 
JohnnyZJ's Avatar
1992 YJ Wrangler 
 
Join Date: Oct 2008
Location: Calgary
Posts: 2,253
gear oil will bring it up a bit.

keep the jeep plugged in that will help
__________________
92 YJ ~ locked/33" swampers
05' WK Hemi limited ~ wifey mobile
13' Chevy Cruze ~ boo
13' GMC Sierra ~ 2.5" lift 33" MTs.
RIP 95 ZJ ~ 33s built/longarmed/locked/awesome Feb 2014 ZJOTM winner
JohnnyZJ is offline   Reply With Quote
Unread 12-17-2012, 10:00 AM   #3
Candymancan
Registered User
1998 ZJ 
 
Join Date: Aug 2010
Location: Virginia
Posts: 3,800
Why are you even using 5-30 anyway they are ment to use 10-30.. ill never understand why ppl do that..
__________________
2013 6.2 V8 Camaro SS 4k miles
1998 5.9 V8 ZJ 160k miles
1998 4.0 I6 Laredo ZJ 210k miles
Candymancan is offline   Reply With Quote
Unread 12-17-2012, 10:03 AM   #4
streetzj
Registered User
1997 ZJ 
 
Join Date: Dec 2009
Location: minnesota
Posts: 317
I guess I've always been told to use 5w-30?

But I've also been warned against using 10w-40 in Minnesota winters...
streetzj is offline   Reply With Quote
Unread 12-17-2012, 10:18 AM   #5
PolkaPower
Registered User
1998 ZJ 
 
Join Date: Aug 2011
Location: The Abyss, MD
Posts: 16,029
Quote:
Originally Posted by streetzj View Post
I guess I've always been told to use 5w-30?

But I've also been warned against using 10w-40 in Minnesota winters...
Why don't you use 5W-40?
PolkaPower is offline   Reply With Quote
Unread 12-17-2012, 10:19 AM   #6
PolkaPower
Registered User
1998 ZJ 
 
Join Date: Aug 2011
Location: The Abyss, MD
Posts: 16,029
Quote:
Originally Posted by Candymancan View Post
Why are you even using 5-30 anyway they are ment to use 10-30.. ill never understand why ppl do that..
It's the same weight warmed up. Just gets up into the motor faster at start up. It seems to have rid me of my cold morning knock I was having.
PolkaPower is offline   Reply With Quote
Unread 12-17-2012, 10:20 AM   #7
Uniblurb
Web Wheeler
 
Uniblurb's Avatar
1996 ZJ 
 
Join Date: Jan 2012
Location: Central, Ohio
Posts: 3,472
I wouldn't even use 10W40 in he summer and follow the spec to use 10W30 year round in all our Jeeps. Always have and always will. And yeah, my oil pressure is just a little low at idle on my 96 4.0 but don't believe it's doing any damage and picks right up when accelerating.

For MN winters believe I'd be using a block/engine heater plugged in overnight if possible.
__________________
96 4.0 ZJ Laredo, 2004 4.7L WJ Limited, 93 4.0 XJ (spare), 96 4.0 XJ (son's)

-Stalling ZJ? 12 things to check before replacing a sensor; the Dirty Dozen
-Crankshaft position sensor multimeter test. & video of testing.
Uniblurb is offline   Reply With Quote
Unread 12-17-2012, 10:54 AM   #8
JohnnyZJ
Web Wheeler
 
JohnnyZJ's Avatar
1992 YJ Wrangler 
 
Join Date: Oct 2008
Location: Calgary
Posts: 2,253
Quote:
Originally Posted by Candymancan View Post
Why are you even using 5-30 anyway they are ment to use 10-30.. ill never understand why ppl do that..
anything thicker in the really cold weather and the jeep will likely not start. you woulnd't see anything like that in Virginia. (unless you guys get -40 degrees there?)

i run 5w30 in the winters. much smoother in most situations. 10/30 in the summer.

keep in mind, the heavier oil will help with pressure but on cold mornings its as thick as molasses. i'd keep it plugged in if you do that for sure
__________________
92 YJ ~ locked/33" swampers
05' WK Hemi limited ~ wifey mobile
13' Chevy Cruze ~ boo
13' GMC Sierra ~ 2.5" lift 33" MTs.
RIP 95 ZJ ~ 33s built/longarmed/locked/awesome Feb 2014 ZJOTM winner
JohnnyZJ is offline   Reply With Quote
Unread 12-17-2012, 11:08 AM   #9
streetzj
Registered User
1997 ZJ 
 
Join Date: Dec 2009
Location: minnesota
Posts: 317
Ok, I think I will go with a 5w for the winters, because it does get well below zero here in Minneapolis. Outstate and northern Minnesota see -40 like your part of Virginia.

I kinda like the earlier idea of 5w-40, but some of you guys seem against a 40w, even with my bad bearings?

And what again does anyone think is the cause of that knocking sound?
streetzj is offline   Reply With Quote
Unread 12-17-2012, 05:19 PM   #10
zander21510
Lord of Retro Machines
 
zander21510's Avatar
1995 ZJ 
 
Join Date: Jun 2011
Location: Dallas, TX
Posts: 1,806
I started using 5w40 Rotella T6 synthetic just to see if it was any good. It got rid of some noises, seems like good stuff. Oil pressure is pretty stable except at warm-up where it can get somewhat low idling after a stop.
__________________
208K (5/26/14)
208k: 4/20/14; 207k: 2/6/14; 206k: 1/6/14;
2013: 197-205k; 2012: 191k-196k
My ZJ Injector Swap HowTo
zander21510 is offline   Reply With Quote
Unread 12-17-2012, 05:34 PM   #11
streetzj
Registered User
1997 ZJ 
 
Join Date: Dec 2009
Location: minnesota
Posts: 317
I'm also thinking of trying that actually. Thanks!
streetzj is offline   Reply With Quote
Unread 12-18-2012, 04:36 AM   #12
Foundrydude
Registered User
1995 ZJ 
 
Join Date: Jan 2011
Location: Flatsville, IA
Posts: 2,692
Be gentle to it when it starts. A bit of knocking on cold start is tolerable. A bit of knocking on a warmed up engine is certain death.

Basically run whatever oil you need to keep it from knocking when warm, and live with whatever it does cold. I wouldn't hesitate to use 20-50 if that's what it took to prevent knock while driving
Foundrydude is offline   Reply With Quote
Unread 12-18-2012, 04:47 AM   #13
streetzj
Registered User
1997 ZJ 
 
Join Date: Dec 2009
Location: minnesota
Posts: 317
Thanks.

I now think the knocking is a lifter, so that's my next thread!
streetzj is offline   Reply With Quote
Unread 12-18-2012, 04:59 AM   #14
LouC
Registered User
2007 WK 
 
Join Date: Feb 2008
Location: NY
Posts: 1,313
I've been using 10w/30 Valvoline Maxlife and the oil pressure on my 98 ZJ 4.0 is 30 psi hot at idle, 40-50 driving..
LouC is offline   Reply With Quote
Unread 12-18-2012, 03:37 PM   #15
Foundrydude
Registered User
1995 ZJ 
 
Join Date: Jan 2011
Location: Flatsville, IA
Posts: 2,692
Quote:
Originally Posted by streetzj View Post
Thanks.

I now think the knocking is a lifter, so that's my next thread!
That's called ticking
Foundrydude is offline   Reply With Quote




Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.