# 5w-30 Vs. 0w-20



## KRainsbarger (Aug 5, 2018)

I read something in here a while back about switching to 5w-30 from the recommended 0w-20. Should I do that? Or is that a dumb decision?


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## ChevyGuy (Dec 13, 2014)

Unless you can find something from GM saying it's OK, I wouldn't do it as long as the engine is under some kind of warranty, or it may void the warranty.


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## Rivergoer (Mar 30, 2017)

Recently discussed ad nauseum here (srtarts a few posts in)

https://www.cruzetalk.com/forum/6-c...ntroductions/239189-2018-hatchback-cruze.html

Happy reading......zzzzzzzzz


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## KRainsbarger (Aug 5, 2018)

ChevyGuy said:


> Unless you can find something from GM saying it's OK, I wouldn't do it as long as the engine is under some kind of warranty, or it may void the warranty.


How would the dealership know what kind of oil I run?


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## ChevyGuy (Dec 13, 2014)

KRainsbarger said:


> How would the dealership know what kind of oil I run?


If the engine has a major malfunction such that the oil used and when it was changed become an issue, they may test it.


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## jblackburn (Apr 14, 2012)

The LE2 switched to 0w20 for the 2018 model year. I don't believe any changes were made to the engine aside from updated pistons and different start/stop programming. 

Basically if yours is a 16/17, it probably won't hurt anything. But I'll stick with 5w-30 in mine. 

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## Taxman (Aug 10, 2017)

jblackburn said:


> The LE2 switched to 0w20 for the 2018 model year. I don't believe any changes were made to the engine aside from updated pistons and different start/stop programming.


What's different about start/stop?


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## snowwy66 (Nov 5, 2017)

Taxman said:


> What's different about start/stop?


They lowered the temp from 41 to 14 before it disables itself. I"m wondering if that was the intention or a fluke and someone accidentally reversed the numbers in the programming.


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## Ma v e n (Oct 8, 2018)

KRainsbarger said:


> ChevyGuy said:
> 
> 
> > Unless you can find something from GM saying it's OK, I wouldn't do it as long as the engine is under some kind of warranty, or it may void the warranty.
> ...


In reality....They won't. They only know what you tell them. 

In my experience since 2001 in the Philadelphia/DE/South NJ metro area, I have NEVER seen GM ask for an oil analysis before authorizing warranty repairs. Only thing I have seen is them ask for receipts for proof of maintenance on engines that had no oil in them, or were suffering from sludge related problems. 

I switched to Mobil1 Extended Performance 5w30 in my car at 2,000 miles. And it will never see 0w20 again. It's far more likely to get dexos2 0w40.


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## KRainsbarger (Aug 5, 2018)

Ma v e n said:


> In reality....They won't. They only know what you tell them.
> 
> In my experience since 2001 in the Philadelphia/DE/South NJ metro area, I have NEVER seen GM ask for an oil analysis before authorizing warranty repairs. Only thing I have seen is them ask for receipts for proof of maintenance on engines that had no oil in them, or were suffering from sludge related problems.
> 
> I switched to Mobil1 Extended Performance 5w30 in my car at 2,000 miles. And it will never see 0w20 again. It's far more likely to get dexos2 0w40.


Does it make any changes in mileage before change or any changes whatsoever? And how long have you ran 5w-30?


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## ChevyGuy (Dec 13, 2014)

I'm not really convinced that 5W-30 is "better protection" than 0W-20. Thicker, yes. But it also flows better which is another aspect of protection. I'd think it depends in part on the tolerances that allow the oil to flow in sensitive areas. In other words, there's no simplistic "better" answer but more of a question of which is the better engineering solution given all the factors involved.


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## Taxman (Aug 10, 2017)

I'd assume the 5W30 was originally chosen to maximize protection, and the 0W20 was later specified because testing showed it's 'just as good' or at least 'good enough to outlast the warranty' while saving a bit on fuel. 

Amateurs would have to group together and do a lot of used oil analysis and combine their results to get any solid idea of how well 0W20 protects. And I doubt GM powertrain engineers are going to tell us exactly what they know.


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## Farmerboy (Sep 2, 2012)

Here are some specs to compare.


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## Camaroman (Jun 18, 2013)

One thing that many uninitiated, drivers even some younger drivers and backyard wrenchers don't know is that the first number 0 or 5 indicates the cold viscosity of the oil. the W is for winter. Back in the days (pre-emission) most standard oils were 10W30 for normal use 10W40 for older or higher performance and 10W50 or 20W50 for extreme performance. tell an older mechanic you're using 0W20 in an everyday engine year round and they would think you are nuts, but with today's synthetics there is a higher protection from these oils than before. that's why you look for the highest industry code level which is an alpha code for the testing used to rate the oil. You can use the newest rated oils in older engines but should never use oils rated with a lower rate code.The owners manual would list the rated code. Often a can will give the rated code on the label or stamped into the lid on old metal oil cans.


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## TDCruze (Sep 26, 2014)

It would take some convincing oil analysis results of 5w-30 and 0w-20 oil from the same manufacturer in the same engine for me to ever consider using 0w-20. Definitely don't think I would use it in a turbo engine. 0w-20 is more about maximizing fuel mileage than maximizing engine life.


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## snowwy66 (Nov 5, 2017)

Given the increased popularity with the turbo and the all might fuel economy

If I were a betting man. I'd say 0-20 could be the future. Oil has been getting lighter and lighter since I first started driving.

My old cars were 20 -50
And 10-40 for the newer years

Then it became 10-30

Then it became 5-30

Now it's 0-20


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## Ma v e n (Oct 8, 2018)

snowwy66 said:


> Given the increased popularity with the turbo and the all might fuel economy
> 
> If I were a betting man. I'd say 0-20 could be the future. Oil has been getting lighter and lighter since I first started driving.
> 
> ...


Actually it's now 0w16, 0w12 and 0w8... Straight Zero is probably what's next.


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## DarylB (Feb 3, 2011)

Test the viscosity of some 20W after 3-5k miles of use and compare it to some 30W oil ran the same amount. You'll find those results interesting. I'd never run 20W oil in a car unless the weather stayed below 32F consistently and the engine didn't have a turbo. I'd never run oil that thin here in the south.


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## TDCruze (Sep 26, 2014)

snowwy66 said:


> Given the increased popularity with the turbo and the all might fuel economy
> 
> If I were a betting man. I'd say 0-20 could be the future. Oil has been getting lighter and lighter since I first started driving.
> 
> ...


I remember the 10w-40 days. It was conventional motor oil and the engines were pretty loose by today's standards. 
Better tolerances, metal alloys and high tech synthetic oils have greatly improved engine protection and lubrication. Allowing lighter, thinner
oils to be used and still triple oil change intervals and allow engines to run many more miles than the engines of the past. 

Maybe, I am too old school to consider going any thinner than 5w-30. 

I still run 5w-30 in one vehicle I own that is 5w-20 recommended. Even in -30 winter weather.


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