Even if Jesus Christ himself told me not to put 5wXX, I'd do it anyway, in fact both mazdas we have received 5w30 and the lowest we had in January was 7°F. Still runs.
2025 Skyactive engine 2.5 NON turbo 0w20 vs 5w30
- Thread starter Bojo
- Start date
there are per say thicker 5w-30 engine oils (euro) and thinner 5w-30 oils (api sq, gf-7 ,rc) that still comply with the J-300 viscosity chart, it can depend on the oil (brand) and specs (it given by blender) , though by all rights you can use a 5w-30 in your Mazda with no check engine light, however in winter climates it maybe better to use a 0w-20 for better quick flow and easier pumpability. to notelow viscosity are built around fuel consumption efficiency along with the wonderful start/stop function on newer cars. just use a sever service oci.
my friend's 16 CX-5 that I've been maintaining has the skyactiv 2.5 NA engine. They bought it used (but it is in awesome condition) and I've had them using 5w30 since they got it. Including winter and summer. The used oil analysis showed that 0w20 was being used previously. Since running the 5w30 all year, no extra wear, you can search for my used oil analysis the wear rates with 5w30 is less now!
The gas mileage didn't drop that much for winter, I was expecting a higher drop, they went from about 28-29 mpg to 24-25mpg. And with the sub-zero temps -10+ Fahrenheit (not talking windchill either) we had last month the only thing the 5w30 did was have a slower starting sound, but fired up and idled quietly. Well quietly until that fart sound flatulent sound goes away after 30 seconds, that thing Mazda uses to run rich to warm up the engine, lol..
so conclusion? I've seen nothing that shows 5w30 wears any different, actually less, than 0w20 including winter time temps. And again, we're talking arctic circle temps here in Michigan!!
They don’t run rich during that cold start cycle – they retard the ignition timing significantly and open the throttle wide to heat up the cat as quickly as possible. Because the NA Skyactiv engines use really long 4-2-1 headers, it would otherwise take way too long to heat the cat and the engine wouldn’t meet emissions.
Here's a technical run-down of the 2013-2016 CX-5 Skyactiv engine with what Mazda is calling "Accelerated Warm-up System or AWS"..
My post was not about the warming up of the car but rather the 5w30 usage in winter. And yes it does make an exhaust flatulent sound when the AWS system is running.
Link is below of the complete bulletin..
Couple of excerpts from the technical bulletin:
"DESCRIPTION: Some customers may complain about an unusual noise coming from the engine compartment for about 20 seconds after a cold engine start. This noise is a normal engine operation for improved exhaust gas emissions. The noise does not indicate a malfunction.
ACCELERATED WARM-UP SYSTEM (AWS): All SKYACTIV-G engines adopt AWS to reduce exhaust gas emissions immediately after a cold engine start. AWS increases the engine idling speed and retards the ignition timing for about 20 seconds after the cold engine start to quickly warm up the catalytic converter. The customer may identify the engine sound during the AWS operation as a unusual noise."
And as I was saying, running rich usually is more fuel but to argue it is pure semantics, either way it does use fuel to warm up, per the bulletin, quoting:
"AWS burns fuel inside the exhaust manifold (A) to quickly warm up the catalytic convertor. The customer may identify the burning sound as an unusual noise"
EDIT: Link attached:
https://static.nhtsa.gov/odi/tsbs/2020/MC-10179079-0001.pdf
My post was not about the warming up of the car but rather the 5w30 usage in winter. And yes it does make an exhaust flatulent sound when the AWS system is running.
Link is below of the complete bulletin..
Couple of excerpts from the technical bulletin:
"DESCRIPTION: Some customers may complain about an unusual noise coming from the engine compartment for about 20 seconds after a cold engine start. This noise is a normal engine operation for improved exhaust gas emissions. The noise does not indicate a malfunction.
ACCELERATED WARM-UP SYSTEM (AWS): All SKYACTIV-G engines adopt AWS to reduce exhaust gas emissions immediately after a cold engine start. AWS increases the engine idling speed and retards the ignition timing for about 20 seconds after the cold engine start to quickly warm up the catalytic converter. The customer may identify the engine sound during the AWS operation as a unusual noise."
And as I was saying, running rich usually is more fuel but to argue it is pure semantics, either way it does use fuel to warm up, per the bulletin, quoting:
"AWS burns fuel inside the exhaust manifold (A) to quickly warm up the catalytic convertor. The customer may identify the burning sound as an unusual noise"
EDIT: Link attached:
https://static.nhtsa.gov/odi/tsbs/2020/MC-10179079-0001.pdf
Last edited:
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That choice is perfect for your situation.
Texas - - - Id go 5w30 -
why not?
4wd
$50 site donor 2026
I have four vehicles with 0W-20. On the fill cap only 
The reason the ignition timing is retarded during AWS is so some fuel is burned in the exhaust past the exhaust valves. But the mixture is not enriched like an old school choke – you can’t do that and meet emissions these days.
How do you burn gas once its outside the combustion chamber?
It’s more like a continuation, it doesn’t start burning outside combustion chamber. The ignition timing is just delayed enough that the power stroke isn’t long enough to extract as much heat out of combustion. So more goes out the exhaust and to the catalytic converter.
With direct injection, you can also inject fuel during the exhaust stroke. That’s how diesels perform DPF regeneration (except those with a dedicated injector in the exhaust stream).
I am not an expert and would like to be educated. But I believe with the Skyactiv engines they just severely retard timing so that the combustion is continuing after the exhaust valve opens. I don't think they are injecting extra fuel and burning it in the exhaust manifold, because there is no fresh air pump that feeds into the exhaust manifold like some cars have (toyotas, bmws and probably others).
I would like to be educated on this though, like I said.
Correct. I was more saying it is possible to burn fuel once it’s outside the combustion chamber.
Thanks for replying. I'm trying to learn more about the strategies current engines are using, including my car which is a 2015 Mazda with the 2.5l. My old M54B30-powered BMW had an air pump that I think it would use to do this, but I was pretty sure my Mazda does not.
Like the one on my Tiguan it’s there to add additional air during a cold start and reduce the emission of unburned hydrocarbons. It only runs during a cold start.
Plenty of videos on YOUTUBE regarding 0W20 V. 5W30. the 5W30 is the clear winner. Better lubrication and cleaner running, and lower wear metals.
My 2¢
My 2¢