0w20 or 5w20

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Ottawa, Ontario
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17 Mazda 6 GT
If you're still under warranty you should follow Mazda's recommendations.
When I went to 0w30 last year, it was done at the dealership and I asked about warranty. They said no problem.

Since my last post, I did an oil change this spring and went back to 0w20. I'm noticing now with the current warm weather we are having that the engine is noisier again. I checked my oil level and it looks dirty, even though I haven't driven much.
It's not scientific I know, but my gut experience is telling me that 0w20 in the current heat we are having is too thin. I also suspect it's more prone to dilution (gas in oil) under these conditions.
I'm definitely changing to 5w30 in the next week or two.
 

madar

Contributor
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2016.5 CX 5 Touring AWD, 2015 SCION XB
No doubt 0w-20 is panther piss oil. But different brands give you different results. I'm switched from Pennzoil PP to Castrol Magnatec 0w-20 in my Scion, difference is night and day...way quieter. I'm running a full synthetic PAO 0w-20 oil in my CX5, virtually no noise at all, oil consumption is way down , gas mileage is up. I don't know how car companies are even specifying 0w-16. That stuff must really be watery.
 

ColoradoDriver

2014 CX-5 Touring AWD - 119k miles
Contributor
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Denver, CO
I've been much happier running 5w30. Less oil loss/consumption between changes was the biggest thing I noticed. I should really get around to another oil analysis, I've yet to send one in with the 5w30.
 
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Mazda CX 5 Touring
The thicker the oil the more it lubricates that's a fact. The thinner oil is recommended primarily to save gas. Going up a little in weight doesn't hurt just don't go as far as 90 weight gear oil. You could run straight 30 weight oil and it wouldn't hurt. In Florida I run 5 or 10w20 in the summer and in winter I run 0 or 5w20. I could run 5w20 all year long with no detrimental results.
 
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Ottawa, Ontario
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17 Mazda 6 GT
The thicker the oil the more it lubricates that's a fact. The thinner oil is recommended primarily to save gas. Going up a little in weight doesn't hurt just don't go as far as 90 weight gear oil. You could run straight 30 weight oil and it wouldn't hurt. In Florida I run 5 or 10w20 in the summer and in winter I run 0 or 5w20. I could run 5w20 all year long with no detrimental results.
10w20, 5w20, 0w20 shouldn't make a difference in warm/hot weather. The second number (20) is the key consideration for hot environments. The first number is something to consider in cold/winter climates.
Personally, I'd run a 30 weight oil in a warm southern climate. I'm definitely switching back from 0w20 to a 30 weight oil in the very near future.

BTW, a blanket statement like the thicker the oil, the more it lubricates, is a bit of a reckless statement.
Today's engine tolerances are much tighter than in the past. At some point in the process, a thicker oil will actually lubricate less because the oil pump cannot pump with enough pressure to get the oil into the tight spaces between the rod bearings and crank journals, as well as the cam shaft bearings. The oil is simply too thick to be effectively pumped into those tight spaces, resulting in lower oil pressures and less lubrication. Thicker oil will also increase engine heat, as the engine and pump have to work harder to overcome poorer oil flow. There's a reason why newer engines don't recommend 20w50 oils anymore.
 
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Ottawa, Ontario
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17 Mazda 6 GT
Follow up: Changed my oil today and went from the water oil (0W20), to 5W30.
It's still early, as I only drove around my neighbourhood, but the engine sounds quieter and seems to be happier.
I'll know better in the morning when I do a cold start. I've found lately that the engine was noisy on morning startups, more than usual.
I also kept some of the old oil and filter, so I may send it in for testing. I suspect due to the short trips I take that there will be a little bit of gas in it.
 
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South Carolina
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12 MZ5 13 CX-5
>thicker oil lubricates better

Sure, if you have large clearances. If you have tight bearing tolerances, thick oil simply can't get in there, and absolutely will cause starvation.

I'm not an engineer, but I have a rudimentary understanding of the subject. I know enough to know I don't know Jack $#!+, Therefore I always follow the instructions of the engineers who designed my engine.

They say use 0W-20, so I'm going to use 0W-20.
 

HardRightEdg

US 2020 CX-5 Touring AWD Soul Red
Follow up: Changed my oil today and went from the water oil (0W20), to 5W30.
It's still early, as I only drove around my neighbourhood, but the engine sounds quieter and seems to be happier.
It would be hard to tell if the difference is in the oil weight or in swapping used oil for new.
 
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18 Mazda CX5 AW
>thicker oil lubricates better

Sure, if you have large clearances. If you have tight bearing tolerances, thick oil simply can't get in there, and absolutely will cause starvation.

I'm not an engineer, but I have a rudimentary understanding of the subject. I know enough to know I don't know Jack $#!+, Therefore I always follow the instructions of the engineers who designed my engine.

They say use 0W-20, so I'm going to use 0W-20.
I too will be sticking with 0w-20 for the same reason(clearance tolerances,etc.) as well as powertrain warranty.

However had anyone considered mixing a couple bottles 0W-20 with some 5W-30 ? Would that not in effect create a 2.5W-25 weight oil? Or is the viscosity more at the molecular level and would create 2 separate oils in your engine?
 
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2019 CX-5 AWD
Mazda states that 5W-30 is also recommended as long as your climate doesn't go below -20F.

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ColoradoDriver

2014 CX-5 Touring AWD - 119k miles
Contributor
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Denver, CO
To my knowledge, 0w20 is just called for in North America. I believe all the other markets are 5w30.

Basically, either is acceptable to use. Been using 5w30 in mine for a few years now.
 
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South Carolina
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12 MZ5 13 CX-5
North America also gets different engines than other areas, hence the different requirements.
 
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Ottawa, Ontario
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17 Mazda 6 GT
North America also gets different engines than other areas, hence the different requirements.
Really? Care to expand on that? How are they different? I'd also be curious to know the difference between the N/A engine and the turbo version, besides the turbo. They are both the 2.5 engines, and if they have the same internals, why is it OK for one to use 5w30 dino oil (turbo), while the other says to use 0w20?
I'm not trying to be a smart Alec here. I genuinely want to know the differences, if there are any.
 
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Ottawa, Ontario
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17 Mazda 6 GT
I too will be sticking with 0w-20 for the same reason(clearance tolerances,etc.) as well as powertrain warranty.

However had anyone considered mixing a couple bottles 0W-20 with some 5W-30 ? Would that not in effect create a 2.5W-25 weight oil? Or is the viscosity more at the molecular level and would create 2 separate oils in your engine?
When I went with a 30 weight oil, it was done at the dealer, and he said there was no problems re: warranty.
 
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South Carolina
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12 MZ5 13 CX-5
I'm specifically talking about the absolute fact that different areas of the world get different drivetrain options. The source is Mazda themselves.
 

sm1ke

Work In Progress..
Moderator
Contributor
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Canada
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'18 CX-9 Signature
I'm specifically talking about the absolute fact that different areas of the world get different drivetrain options. The source is Mazda themselves.

In this case (2.5 NA engine), those different markets (US, Canada, EU) get the same engine. IMO, the only reason they recommend 0W-20 in the US or Canada and not anywhere else for the same engine is because the engine may get slightly better fuel economy with 0W-20.

Source:

This is for the Mazda3, but it uses the same engine. There is also some interesting information regarding oil consumption and what Mazda considers normal.