Running 0W-40 where 5W-30 is specified

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Vehicle is a Chevy Colorado - 3.5L I-5, 147k miles. I really like the looks of the M1 0W-40. Seems to be one great oil at a Wal-Mart 5-qt jug M1 price. I've been thinking about buying this instead of my usual M1 5W-30 for my next OCI. Vehicle has always shown slightly elevated fuel in UOAs since new, so I am thinking that the higher vis will likely be knocked down by fuel after a few 1000 miles anyway. Can anyone think of any good reason NOT to run 0W-40? I'm having a hard time coming up with any "downside". M1 0W-40 looks to be almost at a "heavy 30wt" vis range. My thought is that any impact on fuel economy will be so small that it will be insignifcant.
 
I definitely wouldn't worry about fuel economy which I believe would be insignificant. Wether there's any real advantage I can't comment.
 
Maybe slight decrease in fuel millage and power. When I ran GC in my RX the fuel millage was better. But it was a little sluggish.
 
0W40 instead of 5W30. What's the benefit? If you don't tow a trailer with your truck. However, I see you live in mountain area in PA, then you would probably work the truck harder so use thick oil to increase oil pressure might be a benefit. For clean engine, just use the regular PYB or any name brand 5W30 and do 5k OCI.
 
There would be no advantages just disadvantages to running M1 0W-40 vs say a synthetic in the specified 5W-30 grade.
M1 0W-40 will simply be much heavier than necessary under all conditions.
 
You can mix a Qt of M1 0W20 with the 0W40 to make it thinner. But unless you intend to do 10K OCI, using such good synthetic oil mix is a waste. Like I said, modern SN oil is already a mix of Group III blend if you go with PYB, MotorCraft and other name brand dino. At 5K, these oil should still have plenty of life. The ideal OCI point now is 7.5 for dino and 12.5K for good synthetic oil.
 
Originally Posted By: Maxima97
You can mix a Qt of M1 0W20 with the 0W40 to make it thinner. But unless you intend to do 10K OCI, using such good synthetic oil mix is a waste.

I don't know why you would describe your suggested blend as a "waste". It's actually a good idea is you want to make a higher VI 0W-30 than what you can buy although you'll have to use a lot more than just one quart of M1 0W-20, more like 60%.
 
Originally Posted By: CATERHAM
Originally Posted By: Maxima97
You can mix a Qt of M1 0W20 with the 0W40 to make it thinner. But unless you intend to do 10K OCI, using such good synthetic oil mix is a waste.

I don't know why you would describe your suggested blend as a "waste". It's actually a good idea is you want to make a higher VI 0W-30 than what you can buy although you'll have to use a lot more than just one quart of M1 0W-20, more like 60%.


Is there a thread that breaks down that mix ratio you could link to?

Also, in a towing scenario wouldn't the 0w40 be fine, or very hot climate, or both, if the owners manual specifies it as such?
 
How do you know you will get a higher VI oil by mixing oil. Suppose 0W20 and 0W40 will cost the same to oil refiner, why don't they do it AT NO COST? 0w30 oil is on the perfect spot for light weight vehicle.If cost is the factor, a 5W30 is the ideal oil for passenger vehicle and light truck. If you have a turbo charged vehicle from EU, then 0W40 is recommended. So unless you know what you will get from a mix, don't do it. The oil refiner lab already thought this for you.
 
Last edited:
Originally Posted By: nepadriver
Originally Posted By: CATERHAM
Originally Posted By: Maxima97
You can mix a Qt of M1 0W20 with the 0W40 to make it thinner. But unless you intend to do 10K OCI, using such good synthetic oil mix is a waste.

I don't know why you would describe your suggested blend as a "waste". It's actually a good idea is you want to make a higher VI 0W-30 than what you can buy although you'll have to use a lot more than just one quart of M1 0W-20, more like 60%.


Is there a thread that breaks down that mix ratio you could link to?

Also, in a towing scenario wouldn't the 0w40 be fine, or very hot climate, or both, if the owners manual specifies it as such?

Using a viscosity calculator like Widman's will allow you to determine the percentages of each oil to get the desired final viscosity:
http://widman.biz/English/Calculators/Mixtures.html

Yes using a 0W-40 would be of course fine if the owners manual suggests it but GM doesn't. The specified 5W-30 grade or equivalent 0W-30 with the same HTHSV has more than enough viscosity reserve to deal with the resultant higher oil temp's that may result from some extreme usage like towing in the mountains on a hot summer day.
Also oil shear and possible fuel dilution are also factored into the 30 grade oil recommendation.
Put another way, for more typical none extreme use you could very likely use a 0W-20 oil grade which many OEM's are specifying today including GM.
If one is really concerned about their oil choice not being up to the task simply choose a synthetic oil of the specified grade which will handle high oil temp's better than an off brand dino.
 
Some owners of VQ35s say Mobil 0w40 makes the car run better than any 5w30 spec'd by Nissan. I've never tried experimenting with different weights of oil personally but it is an interesting topic.
 
Originally Posted By: CATERHAM
Put another way, for more typical none extreme use you could very likely use a 0W-20 oil grade which many OEM's are specifying today including GM.


Which OEMs are specifying 20s for the Chevy I5 ?
 
Considering the m1 0w -40 is on the thin end of the 40 grade scale,and thinner at start up I can't see any reason not to use it,other than an imperceptible hit in fuel economy.
The 0w-40 grade is something special. It meets many performance engine specs as well as the euro long drain specs and so on. I am not a Mobil fan at all however that oil is the one that would have me swallow my disdain for Mobil,especially if we could get it for the 25 a jug the American walmarts stock it for.
As far as your particular application unless you are towing or really pushing the engine there may not be any real need for it however it is a world class oil and it certainly won't hurt
 
Originally Posted By: SHOZ
I run 0w40 M1. Hit the pump bypass pressure quite a bit.

Exactly, which is why it's heavier than necessary for any Chevy including a track driven Corvette Z-06.
There simply isn't a scenario where anything heavier than M1 5W-30 is required for a Chevy.
 
Originally Posted By: CATERHAM
Originally Posted By: SHOZ
I run 0w40 M1. Hit the pump bypass pressure quite a bit.

Exactly, which is why it's heavier than necessary for any Chevy including a track driven Corvette Z-06.
There simply isn't a scenario where anything heavier than M1 5W-30 is required for a Chevy.


GM uses M1 0w-40 in their corporate race program Corvette's. So it seems GM feels differently about that.
 
Originally Posted By: Clevy
The 0w-40 grade is something special. It meets many performance engine specs as well as the euro long drain specs and so on. I am not a Mobil fan at all however that oil is the one that would have me swallow my disdain for Mobil,especially if we could get it for the 25 a jug the American walmarts stock it for.


....and that is the whole reason why I am looking at this oil. It's a very robust product that would make me feel better about extended drains, and it doesn't cost a penny more than the M1 5W-30 I am running today.

Can't really believe that the pump would be in bypass all the time for such a minor change in Viscosity (Remember, it's a very light 40 wt).

Compare it to M1HM 5W-30:

Vis @ 40 = 69.2
Vis @ 100 = 11.7

M1 0W-40:

Vis @ 40 = 75 (8% higher)
Vis @ 100 = 13.5 (15% higher)

For comparison, M1HM 10W-30

Vis @ 40 = 78.1
Vis @ 100 = 12

Won't the 0W-40 shear down a bit in operation anyway?
 
Originally Posted By: novadude

Can't really believe that the pump would be in bypass all the time for such a minor change in Viscosity (Remember, it's a very light 40 wt).

What you're not comparing is the more relevant HTHSVs.
M1 0W-40 is 3.85cP vs 3.1cP for M1 5W-30. That's a big difference and it is HTHSV that correlates with oil pressure which is why the oil pump will still be in by-pass mode at elevated rev's at normal operating temp's in your engine.
 
Originally Posted By: CATERHAM
Originally Posted By: novadude

Can't really believe that the pump would be in bypass all the time for such a minor change in Viscosity (Remember, it's a very light 40 wt).

What you're not comparing is the more relevant HTHSVs.
M1 0W-40 is 3.85cP vs 3.1cP for M1 5W-30. That's a big difference and it is HTHSV that correlates with oil pressure which is why the oil pump will still be in by-pass mode at elevated rev's at normal operating temp's in your engine.


Does oil pump remaining in by-pass mode at elevated rpm's at normal operating temps also apply to the 2014 Coyote Ford engine [calling for 5W50] with the track pack from another thread? The reason I ask is its sister engine w/o the track pack calls for 5W20 oil. Thanks.
 
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