0w vs 5w cold weather.

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At what temperature would the 0w have better flow vs the 5w, I am a Mobil oil guy and I loved the 0w 40 FS in my vortec series gm motors. but it's a little thicker than I'd like for my new 6.2 silverado possibly, and it's had a very high count of additives which may not be good for a DI and low speed pre ingtion. I've been monitoring the water temp and oil temp and gm is running these motors hotter than id perfer, water temps of 215 normal driving and 230 at times of hard acceleration. Pulling a trailer id imagine is even higher. That puts oil temps in the 230s. Factory fill is 0w 20. I feel that's pretty thin for these engine opperating conditions. I've been looking at Mobil 1 5w 30 and the 0w 30 afe . I haven't decided yet on which one of the two or possibly a different Mobil oil selection. Winter temps typically don't go below 0 degrees Fahrenheit.
 
0WXX is tested for cold cranking at -35C (-31F) and for pumpability at -40C (-40F).
5WXX is tested for cold cranking at -30C (-22F) and for pumpability at -35C (-31F).

I doubt the two are going to be very different at 0F, although I think Shannow has showed some great curves in the past that gave some real numbers for the two across a wide temp range (and were probably killed by the Photobucket change since then).
 
In Pennsylvania a synthetic 5W-XX oil will be perfectly fine.
That silverado only specs 0W-20 because of corporate average fuel economy regulations, 5W-30 will not do any harm to it whasoever.
 
Originally Posted By: Danno
What are the recommended viscosities from owners manual? Assumes you want to maintain warranty coverage.


Factory recommend oil is Dex1 gen2 in 0w 20, however I didn't list or ask that as a consern as far as warranty coverage, so I would not make that assumption.
 
Does the 6.2 (nice motor BTW) have AFM? Wonder how fussy all that stuff is with thicker oil? These Ecotec3 engines must be designed to run hotter that we're used to, my 4.3 runs 215 and up. Not crazy about seeing the tranny running at 195 and above all the time but the fluid is supposed to be good for it.
 
Yes the new series of gm ecotecs use afm. I don't feel it's an issue or they wouldn't use heavier weight oil in the Corvette with same series of engine, and for track use they spec and even higher weight oil .
 
Originally Posted By: Crobinson16
gm is running these motors hotter than id perfer, water temps of 215 normal driving and 230 at times of hard acceleration. Pulling a trailer id imagine is even higher. That puts oil temps in the 230s.


I don't know about GM engines...

but both of my Ford tow rigs always run cooler oil temps than coolant temps
under "Normal" (no load driving)
and WAY hotter oil temps when towing.

You are only guessing at oil temps until you come up with a way to actually monitor/verify it.
 
Originally Posted By: Linctex
Originally Posted By: Crobinson16
gm is running these motors hotter than id perfer, water temps of 215 normal driving and 230 at times of hard acceleration. Pulling a trailer id imagine is even higher. That puts oil temps in the 230s.

I don't know about GM engines...

but both of my Ford tow rigs always run cooler oil temps than coolant temps
under "Normal" (no load driving)
and WAY hotter oil temps when towing.

You are only guessing at oil temps until you come up with a way to actually monitor/verify it.


It's not an option on your MFD?
I keep mine up almost all the time.
 
If winter temps stay above 0F, the 5w-xx grade will be fine. If you can't spin the motor quickly at those temps with that winter grade, you need to perform some battery/starter maintenance.
 
here in PA i use 10-30 group III oils mostly, no starting issues + better protection than the thinner xxW-20 when hot oils!!! on that note its known that any oil except real synthetic group IV PAO + group V ester + other oils continue to thin after the advertised viscosity tested @ 212F, + actually are thinner in hotter areas of an engine on a regular basis!!
 
Originally Posted By: benjy
here in PA i use 10-30 group III oils mostly, no starting issues + better protection than the thinner xxW-20 when hot oils!!! on that note its known that any oil except real synthetic group IV PAO + group V ester + other oils continue to thin after the advertised viscosity tested @ 212F, + actually are thinner in hotter areas of an engine on a regular basis!!

Uhh, all oils continue to thin as the temperature is increased.
 
Originally Posted By: Virtus_Probi
I doubt the two are going to be very different at 0F, although I think Shannow has showed some great curves in the past that gave some real numbers for the two across a wide temp range (and were probably killed by the Photobucket change since then).


I've found a new set, and will try to get some off photobucket when I've got time...



This one was good, in that it showed how a bunch of different oils thickened with the cold, affecting delivery times.

Plus had a regression equation for that particular engine in the test cell.



Points of note is that the regression equations are on the crazy end, the cold pumping end, so their absolute use in the freezing and above range aren't there.

Note also, it's in whole poise, not Centipoise.

So take M1 0W40 and M1 5W30 at 0C (I'll just use Cst=Cp, it's close enough).
5.62P versus 6.33P - Delta = 0.71

Delta ROAT - 0.072*0.71 = 0.05sec
Delta 3bar - 0.062*0.71 = 0.04sec

Like I said, the formulae are around the actual measurable part of the curve...in the flat part, there's no difference with a PD pump.


For the cold end, note that J300 MRV (flow to the pickup is about 600P depending on grade), and that MRV halves with every 5C temperature increase roughly.
 
When you typed the first sentence of you post...
I don't know about gm engines....
That should have registered to you not to type anymore. Not talking about Fords, and oil temps are easily monitored.
 
Last edited:
Shannow's graphs are a little over my head....Is it safe for me to assume that a 5w20 is not significantly different than a 0w20 at 0*F?....Let's use Mobil 1 as an example...How about Mobil 1 0w20 vs MS5K 5w20 (Mobil's dino) vs. M1 0w20 at 0*F?
Thanks...and sorry for my ignorance.
 
Originally Posted By: kschachn
Originally Posted By: benjy
here in PA i use 10-30 group III oils mostly, no starting issues + better protection than the thinner xxW-20 when hot oils!!! on that note its known that any oil except real synthetic group IV PAO + group V ester + other oils continue to thin after the advertised viscosity tested @ 212F, + actually are thinner in hotter areas of an engine on a regular basis!!

Uhh, all oils continue to thin as the temperature is increased.

Exactly so why is everyone so concerned with using a super light weight oil for start up when that's Great but not so Great after a hour of heavy pulling. I am with Bengy 100%.
All this wear [censored] at start up, tell you what 100% of wear happens when metal touches metal, hot or cold.
 
I know three people using 0-20 in there GM V8 engines(including my son who lives in Florida) with very good results. You probably are way over thinking this issue.
 
BTW. I am originally from PA too and saw it so cold you stick to metal. I never had a issue with oil too thick and I spent time with Detroits with straight 40 wt oil in them.
Fuel freezing will be a bigger issue than oil and cold starts. It's just rediculas if you have real life experiences and realize it's all cafe.
I also run 10w30 in my 5w20 speced Dodge Hemi, since day one and it's still under warranty. No problems whatsoever and since it is never cold here in Florida, it never will be.
 
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