I did swap to both those gear oils, you will appreciate them. The trans fluid make the shifts buttery smooth at any temp.
Good low volatility 10w-30 for a Skyactive GDI engine?
- Thread starter RavenTai
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Oil temperature is not monitored on stock but Miata’s are tracked a lot and that oil temperature is closely watched. 30% of the heat is exchanged by oil, and the flow of oil. Tracked cars can see oil temperature decrease.
So… not ot say this is true but oil flow is engine cooling and temperature is always changing the viscosity. Target coolant temperature is close to oil temperature on street but tracked cars have much higher oil temperatures than coolant. Some guys run 0w-20 to get the benefits. Others run 0w-30 or 5w-30.
Does Engine Oil Flow Affect Operating Temperature? – McNally Institute
www.mcnallyinstitute.com
Everything you say is true, and that article is certainly correct in saying that overly viscous oil can increase temps. Likewise extremely low viscosity oils can increase temps because you don't have enough film strength to prevent metal to metal contact.
But I don't think either of those conditions are relevant here. 5W-30 isn't overly viscous and 0W-20 isn't an extremely low viscosity oil. Both are in the reasonable viscosity range for that engine. Both will have almost identical specific heat capacities and will therefore be essentially equal in terms of their contribution to cooling.
At the end of the day, hydrodynamic drag might rob you of an additional horsepower or so with the somewhat thicker oil (maybe a little more or less) and that's going to be the contribution to increased oil temp. That 1hp (ish) is small compared to the thermal dissipation of the entire engine, so I still don't see that you're going to note much difference in oil temps unless someone's got some empirical evidence that says otherwise.
I can see that if I were tracking the car I'd probably like to pick up that extra horsepower (it's almost free), but otherwise I'd probably err on the side of slightly better engine protection, particularly in a hotter climate like Mexico.
It is moot point… I just like to understand why the engineers choose to say what they do. Personally do not like to play a guess why game. USA, Canada and Puerto Rico 0w-20, Mexico SM or higher 10w-30.
As an engineer I tend to agree.
It can be easily managed if you just do regular intake spray cleaning. 188k with no problems and I use full SAPS oils almost exclusively. Pretty much any GDI engine needs frequent fuel injector treatment and intake valve cleaner treatments if you don't want it to run like crap after 60k.
It may be due to what’s most widely available in a local area. There is also the consideration that Mazda used 0W-20 on the mpg tests, so that is what has to recommended in the US.
Yes, refer to the CAFE award letters posted here in the past to see just how aggressively the automaker must promote the exact grade used to demonstrate fuel economy. It goes beyond the manual.
Plus as far as engineers go - wear graphs have been posted here multiple times showing that below an HT/HS of about 2.6 wear starts to significantly increase. Engineers aren't dictating the grade here in the sense that they design an engine for a specific power density and then decide on a specific HT/HS, it is that the corporation is mandating the use of thinner oils in order to meet progressively more strict corporate fuel economy targets. It's not malicious any more than body designs are also dictated by drag coefficients, but it's where the challenge now lies. What engineers are doing is that they are busy designing engines that can tolerate thinner and thinner oils. It represents a shift in priorities.
Good to see this. I try to comment on every ND Miata post to encourage the owner to change the gear oil. Trans oil is a good idea too. Both the gearbox and final drive on these cars are proven to run quite hot. Frequent fluid changes on both should help them to survive longer.
Jackson_Slugger
$50 Site Donor 2022
Are you going to buy the 10W-30 "SM" in Mexico too? LOL
It's a completely different market where synthetic oils are very expensive and may not even be attainable to the average person, so they're stuck with formulating older base oils that wouldn't be allowed under current API spec's so the majority can afford it...
The 10W-30 doesn't have many spec's because it is a dead end weight no OEM has recommended since the Chrysler HO engines about 10-12 years ago....
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The 2019 came out with the fifth revision of the MT for the Miata and that looks like a winner. I have Red Line MT-90 in… works great.
Agreed. I'm glad that Mazda stayed on top of revising this transmission. Talk about one hell of a teething issue.
Regardless of the revision level, they still run hot. MT-90 is no doubt up to the task. The high heat just means a shorter fluid change interval, irregardless of fluid used.
There's no benefit to running 5w30 on the street, in fact the car felt slower. xW20 is nothing to be feared...
2019 Mazda MX-5 Miata - Mobil 1 EP 0w20 - 5k OCI/9 Months
This is the third oil change on this vehicle. M1 108a was the filter removed. Oil was initially changed at 3k (PP), and then 7k (M1 0w20EP). Due to COVID, my driving has been way down. Normally driving around LA is mostly city driving, however some of the average mileage was more highway. This...
bobistheoilguy.com
I don’t fear it but a somewhat higher HT/HS is a tangible benefit in my book. And I’ve never felt the car being “slower” with a 30-grade.
Just how much slower do you have something to offer us like maybe a 1/4 miles ET and speeds?
Just to add, while these SkyActiv engines rev up quickly, for the most part they have a easy life. Even on the highway the RPMs are low.
If the car is going to be tracked or similar then a step up in grade would be prudent. For everyday driving including some higher throttle episodes like going up long hills for example, a 0w-20 will do the job. Even in hotter climates it will be fine.
I tend to believe that the temperature charts we see for oil grade recommendations are remnants of the past when straight grades were the norm.
Referring back to the OP (post#1)… There is specific viscosity called for in the Operator’s Manual quote. In my 2019 Miata Owners Manual same wording but for Mexico the specific viscosity was 5w-30. (now 10w-30) Then says if you cannot find 10w-30, put 5w-30 in. The 2019 OM says cannot find 5w-30 then 5w-20
That is specific viscosity recommendations for the same vehicle.
Climate is variable from desert, Puerto Rico to Canada and one viscosity recommended 0w-20.
The variable I have not heard is the fuel supplied.
That is specific viscosity recommendations for the same vehicle.
Climate is variable from desert, Puerto Rico to Canada and one viscosity recommended 0w-20.
The variable I have not heard is the fuel supplied.
Do you really think the engine would notice the differences between a 10w-30 at 30°C and a 5w-30 at 20°C ?
The engine knows nothing, as both of these oils weight 10 CST at 100°C.
I would pour the lower Noack in this engine, thinking it will be the 10w-30.
The engine knows nothing, as both of these oils weight 10 CST at 100°C.
I would pour the lower Noack in this engine, thinking it will be the 10w-30.
So why did the viscosity requirements change for Mexico to 10w-30. Personally do not care but that should be a neon light that a decision was made with higher thinking than you or me. (or oil experts here) They are specific…
OVERKILL
$100 Site Donor 2021
It's likely just due to market availability. Japanese oil requirements tend to be pretty loose, typically not having any of their own approvals and just going by the basic API ones.
Remember, before CAFE, we used to be given ranges of viscosity in manuals and the range for 5w-30 and 10w-30 had a heavy area of overlap, but of course 5w-30's were far more likely to shear back then than they are now.
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