Variable Displacement Oil Pump, 5W-30 to 0W-20?

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Hi all, first post here. I live in Ottawa, Canada, and have a one year old Chevy Cruze Eco manual, with the 1.4L Turbo engine. The car has been great and is averaging 44 MPG for the entire first year of ownership, thanks to my careful driving habits and easy low speed commute.

The car calls for 5W-30 Dexos1 oil. I drained the FF at ~2500 miles (4000kms) and put in M1 5W-30. The OLM had me changing oil around 9950 miles (16000kms) based on my driving. I did so again with M1 5W-30 and a Delco filter. So far so good with roughly 13000 miles (21000kms) now. For the record, I have no loyalty to Mobil1 other than it was the factory fill in my Corvette (so I use there also) and it is cheap and easy to get when on sale at Canadian Tire stores.

I bought this car primarily as a fuel efficient commuter. I read through the "Oil University" posts here and found the information quite interesting WRT start-up viscosity and I'm wondering if I could use a 0W-20 in place of the 5W-30?

My primary driving is very easy, with the engine rarely ever getting above 2000 RPM. Our climate ranges from bloody cold to (relatively) hot and very humid. In the winter months my car barely and sometimes doesn't get to full operating temperature by the time I get to work, even with both upper and lower front grills blocked off and limited use of the heater. Other Cruze owners report oil temps over 250F in hot climates at highway speeds with AC use.

As far as I know WRT engine oil, four key differences that make this engine different from most are:

1. Turbocharger
2. Small displacement
3. Water-to-oil warmer/cooler
4. Variable displacement oil pump

1 & 2 tend to beat up on oil, from what I understand, especially since the Cruze isn't exactly a light car (just over 3000 lbs in Eco trim). 3 seems to indicate that oil temps will rise faster and remain more stable than they would if the engine was not so equipped. Also, I use the OEM oil pan heater in the winter, though it's a low power 200W unit that does little more than keep the oil pan "warm". I do not have the ability to use the oil pan heater at work.

Number 4 is what puzzles me the most in this situation. The variable displacement oil pump operates to maintain a certain pressure to the lower crank case. An oil fed regulator varies the pump displacement and references the oil pressure after the main/rod bearings but before the cylinder head:

http://vauxhall.workshop-manuals.com/astra-j/index.php?id=4646

WRT to engine efficiency: Would the thinner oil require a higher pumping volume from the oil pump to maintain the desired pressure? The way my mind works, this would make sense. If this is the case, would there be any efficiency benefit at all from using a 0W-20 oil over a 5W-30?

WRT engine protection: Would the thinner 5W-20 compromise engine protection at operating temperatures? With my regular driving style being so easy I would assume NO, but I would like to make sure the car is still capable of operating at higher speeds in higher temperatures. With crank case oil pressure regulated precisely by pump displacement, extra flow may be a benefit? Would the lower hot viscosity be an issue for the cylinder head or turbocharger?

Yes, I realise 0W-20 is not Dexos1 labelled… I'm not contemplating the warranty, I'm wondering what's best for my driving with an eye on efficiency and cold start protection. I put about 12000 miles (20000kms) per year on the car and would rather use the same oil year round if possible. Looking for the advice of the experts here. Thanks!
 
With your turbo engine, I would not use anything lower than what is spec'ed in your manual. Dexos 1 does include 5w-20 on their approved list but with the turbo, I would use the viscosity that is speced by GM. FWIW---Oldtommy
 
Great choice of vehicle, typically well reviewed and a great tight little car.

With the high tech in that very small but high output engine I cannot imagine deviating from the factory spec. Dexos is a very tough oil, and any brand is going to be pretty nice for you.

The turbo is the hard part for the oil. I would also worry about the variable displacement pump working harder to maintain a certain oil pressure with thinner oil.
 
First...
welcome2.gif


Personally, I don't think a switch to a Xw20 would net much in the way of fuel mileage. What you are doing is probably working very well, that pan heater will likely make more difference than you believe on those cold mornings. I do agree that your use could very likely allow for use of a Xw20 in the winter but I would recommend a pressure and temperature gauge to keep an eye on it. Or a cheap OBDII bluetooth connector and the Torque app on an Android device, not sure what your computer reads and you still might not get oil pressure this way which I would think would be the preferable of the two.

As far as the oil pump and the other points, what you said sounds about right to me but I'm no engineer.

There actually are a couple 5w20s and at least one 0w20 on the dexos1 list I believe.
 
Generally speaking, yes I believe in the case of a variable displacement pump, in order to maintain constant pressure, a thinner viscosity oil would result in a higher flow of oil in volume per minute, when compared to a thicker oil.

I'm not sure which would benefit your engine more, but Mobil 1 AFE 0W-20 and several different 5W-20s are now Dexos1 approved.

On an unrelated note - I've visited Ottawa many times on business, it is one of my favorite cities. I make it a point to go drink a Keith's at this little bar below Sparks St whenever I'm there.
 
Quote:
My primary driving is very easy, with the engine rarely ever getting above 2000 RPM


See that's where the problem lies. While constant low RPMs are nice and easy on oil, accelerating from such low RPM's certainly requires a certain amount of hydrodynamic film strength. And with Cruze's nice low end torque, I would imagine that it can accelerate effortlessly probably even below 2k RPM.
That's where 5w30 and dexos 1 requirement come into play and guarantee that a certain margin of safety was tested for to avoid boundary condition.
If you decide to run anything thinner than that, you're in an uncharted territory.
 
The variable displacement pump causes a more viscous oil to cause less of an efficiency reduction than a less viscous oil than would be the case with a typical oil pump. The pressure will initially be higher with the more viscous oil and then the system responds by reducing the pump's oil flow rate, thereby reducing pressure to some amount. My answer to your question about this is that assuming the scenario is that the engine is started in very cold temperatures, both thinner and thicker oils may require the pump to reduce the oil flow rate and in order for equal oil pressures to be the case, yes, the thinner oil will have a higher flow rate.

The engineers already thought of many ways to improve this car's efficiency and they specified a 5W-30 oil instead of less viscous ones. I would use what they specified. In the winter, you could probably safely use a less viscous oil but I would not expect to see efficiency gains that are worth the mental stress and warranty implications that deviating from the specified oil (in the thinner direction) may cause. In the warm months I certainly would not use an XW-20 oil. 250F oil temp. is quite high and this engine reaches high torque at low RPMs which reduces oil film thickness in the bearings compared to higher RPMs.
 
Originally Posted By: Blue_Angel


The car calls for 5W-30 Dexos1 oil.


That's what I'd use.

Welcome to Bitog.
 
Since your in Canada, how about something like PP 0w-30, Flow's better in the cold, yet robust enough for the turbo...
If you don't care about possible warranty issues, that would be my vote.
 
With that tiny high tech turbo engine use the best 5W30 Dexos approved fully synthetic you can find. What you are using now is very good, the only step up to me would be Pennzoil Ultra.
 
I wouldn't use 0w20 in a Cruze turbo. Since you're in Canada though, you might benefit from a 0w30 oil. Mobil 1 Advanced Fuel Economy 0w30 is one such oil. Idemitsu also makes a 0w30 which is on the Dexos approval list, though I have no clue where you'd buy it.
 
There is a reason why GM chose 5w30 for this vehicle application - stick with the OEM spec.
 
Oil pressure is the vehicle through which oil is supplied to the engine, it's not a lubrication paramater in it's own right.

Variable oil pump will deliver the required volume to get the pressure, and the thinner oil will have less resistance, so flow WILL go up most cewrtainly...

But oil pressure doesn't lubricate bearings.
 
Originally Posted By: ernied
why don't you guys just put in what the manufacture recommends or go to college and become an enginer if you doubt them.


Tried that, and it holds no sway on BITOG...
 
Thanks for the welcome everyone! You guys don't waste any time jumping into a thread!

Originally Posted By: JAG
The engineers already thought of many ways to improve this car's efficiency and they specified a 5W-30 oil instead of less viscous ones. I would use what they specified.


I have a very healthy respect for the Engineering and development that goes into an automotive product. I spent several years in automotive, unfortunately not in powertrain, and got a very good inside look at how thoroughly things are done. I do in fact believe 5W-30 is an excellent oil for this engine, especially a proven full synthetic.

Originally Posted By: KrisZ
While constant low RPMs are nice and easy on oil, accelerating from such low RPM's certainly requires a certain amount of hydrodynamic film strength. And with Cruze's nice low end torque, I would imagine that it can accelerate effortlessly probably even below 2k RPM.
That's where 5w30 and dexos 1 requirement come into play and guarantee that a certain margin of safety was tested for to avoid boundary condition.


The turbo boost on the manual cars ramps up slowly and hits peak around 2500 RPM. The automatic cars hit full boost sooner, by around 1800 RPM. I drive gently, but I see where you're going with this.

Originally Posted By: michaelluscher
Since your in Canada, how about something like PP 0w-30, Flow's better in the cold, yet robust enough for the turbo...
If you don't care about possible warranty issues, that would be my vote.


This is likely a good compromise. 0W-30 is actually specified in the Cruze manual for use in cold temps, trouble is the only Dexos1 approved 0W-30 is M1. I'm not quite ready to toss the warranty just yet, so I'd have to cross the border and buy some 0W-30 M1 to go that route since it's not sold in Canada. Not impossible, and it's MUCH cheaper.

Originally Posted By: gpshumway
Since you're in Canada though, you might benefit from a 0w30 oil. Mobil 1 Advanced Fuel Economy 0w30 is one such oil. Idemitsu also makes a 0w30 which is on the Dexos approval list, though I have no clue where you'd buy it.


I looked through the Dexos1 list on line and sure enough M1 0W-20 and 0W-30 are both on the Dexos1 list! I was at Walmart looking at 0W-20 the other day and it didn't say Dexos1 on the bottle... old stock maybe? Idemitsu is on the list too... too bad they don't provide a link to who sells it!

It sounds like there's a lot of nervousness about straying from the 30 weight, and for pretty good reasoning. It looks like the best thing may be a 0W-30 to make sure things stay happy at high temps. If I decide to go that route I'll need to pick up M1 0W-30 in the US if I want to keep my warranty preserved.

Going from M1 5W-30 to M1 0W-30... will there be much difference at all in cold start up flow? Based on the specs Mobil is advertising it looks pretty similar. Since the 0W-30 is so much cheaper in the US it's not really that big of a deal I guess... whenever I'm there I can pick up a bottle or two.

Originally Posted By: ernied
why don't you guys just put in what the manufacture recommends or go to college and become an enginer if you doubt them.


OK, sounds good. And while we're at it let's no longer bother with UOAs, we'll shut down sites like BITOG, and from now on we'll just go to the dealer for a factory fill of whatever the experts there recommend whenever the OLM hits 0%. Perfect, and so simple! After all, other people always know what's best and understanding something is just asking for frustration and wasted time...
 
Originally Posted By: Blue_Angel
Thanks for the welcome everyone! You guys don't waste any time jumping into a thread!

Originally Posted By: gpshumway
Since you're in Canada though, you might benefit from a 0w30 oil. Mobil 1 Advanced Fuel Economy 0w30 is one such oil. Idemitsu also makes a 0w30 which is on the Dexos approval list, though I have no clue where you'd buy it.


I looked through the Dexos1 list on line and sure enough M1 0W-20 and 0W-30 are both on the Dexos1 list! I was at Walmart looking at 0W-20 the other day and it didn't say Dexos1 on the bottle... old stock maybe? Idemitsu is on the list too... too bad they don't provide a link to who sells it!

It sounds like there's a lot of nervousness about straying from the 30 weight, and for pretty good reasoning. It looks like the best thing may be a 0W-30 to make sure things stay happy at high temps. If I decide to go that route I'll need to pick up M1 0W-30 in the US if I want to keep my warranty preserved.

Going from M1 5W-30 to M1 0W-30... will there be much difference at all in cold start up flow? Based on the specs Mobil is advertising it looks pretty similar. Since the 0W-30 is so much cheaper in the US it's not really that big of a deal I guess... whenever I'm there I can pick up a bottle or two.


Not much difference, honestly. Below -10*C the 0w30 will start to show benefits.
 
Originally Posted By: gpshumway
Originally Posted By: Blue_Angel
Thanks for the welcome everyone! You guys don't waste any time jumping into a thread!

Originally Posted By: gpshumway
Since you're in Canada though, you might benefit from a 0w30 oil. Mobil 1 Advanced Fuel Economy 0w30 is one such oil. Idemitsu also makes a 0w30 which is on the Dexos approval list, though I have no clue where you'd buy it.


I looked through the Dexos1 list on line and sure enough M1 0W-20 and 0W-30 are both on the Dexos1 list! I was at Walmart looking at 0W-20 the other day and it didn't say Dexos1 on the bottle... old stock maybe? Idemitsu is on the list too... too bad they don't provide a link to who sells it!

It sounds like there's a lot of nervousness about straying from the 30 weight, and for pretty good reasoning. It looks like the best thing may be a 0W-30 to make sure things stay happy at high temps. If I decide to go that route I'll need to pick up M1 0W-30 in the US if I want to keep my warranty preserved.

Going from M1 5W-30 to M1 0W-30... will there be much difference at all in cold start up flow? Based on the specs Mobil is advertising it looks pretty similar. Since the 0W-30 is so much cheaper in the US it's not really that big of a deal I guess... whenever I'm there I can pick up a bottle or two.


Not much difference, honestly. Below -10*C the 0w30 will start to show benefits.


AFE 0w-30 is not available in Canada. Gotta do the Caterham blend if you want a 0w-30 from mobil
 
Originally Posted By: JethroBodine
5w30...why fight it? KISS


Amen. It's not broke, but let me try to fix it anyway.
 
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