Optimal oil for lethally cold weather, Jeep 4.0L, parked outside

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Dec 26, 2005
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Upper Midwest
I believe “The Lake Effect” is more of a snow issue. Here is a screen capture showing the areas around the Great Lakes, but even so, South Bend is just outside the region that gets snow the most.
Yes it can be a horrendous drive around the southern shores on I-94.
 
Joined
Feb 25, 2019
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Cypress, Texas
Does your engine burn oil. If a little like a quart every 3-4k i wouldn't be afraid to put in platinum 0w-20 or a 0w-16 like m1 if it burns nothing. If it does burn a little more id just go for platinum 5w-30. I only used 10w-30 since it typically doesn't go below 30 where I'm at. Switched to 15w-40 but the freeze made me rethink that, on a 5w-40 now.
 

blupupher

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Katy, Republic of Texas
A serious question from a southerner guy, isn't 10w oil supposed to be fine till like -15°F. I know it will be thicker than a 5w at that temp, but is it that much of a difference?
The record lows are just below the threshold of 10w oil, so I guess you should be prepared for that, and in that case, I would say something like T-6 5w-40, it has the better cold weather starting ability, and the thicker 40 weight which that era of Jeeps seem to like, and is not that expensive overall.
 
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What did Jeeps in Indiana use back in 1988 use ? 19-23º F isn't "cold" to a vehicle engine either. Keep using 10W-30 or at best, 5W-30.
 
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Oct 9, 2004
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Cincinnati, OH, USA
I don't remember which lake, but South Bend is supposed to suffer from a "Lake Effect" climate. It's unusually cold for Indiana.
Actually, when the wind blows over the (unfrozen) lake it gets warmer-it's the (sometimes biblical) snow you have to watch out for! Perfect 4WD Jeep weather! The upper Great Plains (ND, SD, MT, MN) get a lot colder. AK is still the king of US cold, though.
 
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Sep 17, 2002
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Lakeville, MN
Previous owner of an '88 Cherokee pioneer - I miss it at times.

Really despite the premise of how bad the cold is, a plain old 5w30 oil or 5w40 if you like will serve with no trouble. The 10w30 would actually be ok too but the 5w30 gives a buffer a bit... worked fine for years in my '88... and I guarantee it's colder here than there (per friend who attended ND and grew up and lives here...)
 
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Massachusetts
A serious question from a southerner guy, isn't 10w oil supposed to be fine till like -15°F. I know it will be thicker than a 5w at that temp, but is it that much of a difference?

We had a Scout skiing trip up to the White Mountains during a cold snap in Jan '20. I towed the Troop trailer with my truck.

We arrived on Friday and the overnight low was -22*F. The next morning I fired up the 'ol Coyote with PP 10W30 and it started fine. I don't put a lot of miles on the truck and do yearly changes. I didn't remember the 10W30 was in there when I volunteered to drive. No biggie.
 
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Sep 9, 2020
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Scottsdale, AZ
Quick google search for that wonderful multi-viscosity temp chart from owners manuals of the days of yore (when not every owners manual said only 0w20) says 10w30 would likely be fine, I think it goes to -20° Or -25° F. Would probably throw M1 Euro 0w40 in that engine and call it good.
 
Joined
Mar 11, 2016
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Location
Denver, CO
Shell Rotella has served me well in my 4.0s over the last 11 years.

I ran T4 10W30 conventional for many years while living in Chicago, affectionately known as Chiberia during the winter months, down to as low as -17* F (I know, I know it’s nothing compared to the great frozen north that is Canada) with zero oil related issues.

I have since switched over to T6 5W40 full synthetic and have had equally positive results here in Denver, where it drops down below zero (barely) once or twice a year. I did a Blackstone UOA on my last change that is posted in the UOA section if you want to take a look. That interval had several single digits / low teen cold starts for comparison.


I did try M1 10W30 when I first got a 4.0 and I can attest that, that oil does make a racket in the 4.0. The lifter tick that is normal on healthy 4.0s is greatly exasperated and becomes very clanky on M1. It quiets right down with Rotella, quite for a 4.0 at least.
 
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Joined
Feb 6, 2021
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Massachusetts
5w30 works fine for me even at -15f. If you're concerned just go with M1 AFE 0w30 or FS 0w40, both M1 flavors have pour points lower than regularly encountered on this planet. Give it 60 seconds after cranking, then drive gently (stay below 3k RPM).
 
Joined
Jan 9, 2005
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Sarasota, Florida
I believe your car has an oil pressure gauge. Read my "Thick vs Thin" chapters and you will be able to select the correct grade for your application.

ali
 
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