So, did my first oil change on my 2021 CX-5 non-turbo. Did it at 5.25K but since I was down a quart at 3K, one could argue that I did it earlier than indicated, effectively. You could also argue the other way; e.g. that since I was operating on less than 4.8quarts of oil for some period during first months of driving, overall, I the addition of a quart does not make up for the fact that I had less than 4.8qt of oil in crankcase for some period. Either way. However you want to argue.

Oil was half-dirty (at most) to my eye, but OK, get the first batch out with whatever metal shavings, special break-in oil portion, etc. that was in there. Moving fwd, I do NOT expect to change synthetic at 5K. I don't see it as necessary. I will go at least 7.5K with ordinary, mostly-highway miles. (No. I did not send to lab for analysis. I don't see that anything special went on in that first 5K miles and I can do without special enlightenment. Forgive me Father Callisto).

I note that the regular 2.5 Liter Skyactive Engine does NOT appear to have an oil cooler behind the filter. I imagine that the 2.5T does have the engine oil cooler. I do question the effectiveness of a cooler that uses circulating engine coolant to cool the engine oil. Since the circulating coolant is at 210 degrees (at least) at normal operating temperatures, pleas explain the physics (Dear Callisto) by which 210 degree engine coolant in a tiny cooler apparatus, cools engine oil at operating temperature (whatever that is)? What is the temp difference between the engine oil and the engine coolant (at each fluid's respective op temp that would result in significant cooling. In addition, same comment for Trans Cooler which presumably is resident for both NA and Turbo 2.5T (since it has to do with the Tranny fluid, not the engine oil). How does that meaningfully cool trans fluid using 210 degree engine coolant?

Please provide full physics 'white paper' with explanation! (OK. Only kidding. You know I love you, Callisto.) But would like some thoughts on this.

Hopefully, this will end the 'Sparkplug' thread. Bring your asses over here. Thank you.

Best, Reuben

 

Further, I forgot to add this part.

I used 5W-30 Costco/Kirkland synthetic and a Robert Bosch filter. I guess Mazda will severely reprimand me and void my engine warranty? That would be a bad outcome.

As to 5W-30 vs. 0W-20, I imagine the MPG may decline, I don't know how much. But it is Spring here in incredibly beautiful New Jersey, the urban/industrial wasteland pictured in the movie 'BladeRunner'. So, the 0W does not confer much advantage since it is not Winter. As far as 30W vs 20W, on the other end, I have somewhat more viscosity and "cling' on the moving parts while at rest overnight. Is that not a plus for reducing engine wear on start-up?

Thank you my Mazda Brethren. Let's argue in this thread for days, OK? Bless All, Reuben

 

The recommended OCI on the NA engine is 7500 miles.
Oil temperature of 210-225 is about normal for many engines without oil coolers. Not a
problem with synthetic oils.
The aluminum block could help keep oil temps low as the coolant enters the block first then
flows up and through the head.
No worries. Keep an eye on oil use as Mazda changed valve seals recently and they aren't up
to their usual standards.

My 2¢

 

Thank you Dennis. Appreciate it. I was still wondering about why Mazda engineered an oil cooler that uses 210 degree (or more) engine coolant circulating through it to cool the engine oil. I don't see how that effectively cools the oil. They are at the same temperature! Or close to it. Best, Reuben

Also wondering if anyone has any thoughts on the 0W vs. 5W viscosity oil question.

Thank you!!! Reuben

 

Given quality brand of oil, either will work fine. I doubt you'd need it NJ.
0W has more viscosity improver additives and MIGHT shear down quicker, but
generally not a problem with normal OCIs.
If you move to Canada then the 0W might be a good choice for winters.

​​​​​​​My 2¢

 

From my understanding the radiator itself has no connection to the oil cooler. The oil cooler is a tiny radiator labyrinth through which the engine oil runs - it is air cooled (no coolant). I know that is how my air cooled scooters worked anyway. Here is a video of one like I described being installed on a Miata:


I am sure others (ahem Callisto...) will step in quickly if I am incorrect.

 

The oil cooler on the turbo engines sits in front of the radiator, more or less. A small
radiator for the oil. Oil only flows through there. If I'm not mistaken, there is a thermostat
for the cooler. There is none on the NA engines.

My 2¢

 

There you go - so it is completely separate from the radiator, no coolant involved in the process.

 

Thank you Mr. Wendt. Appreciate it. Best. Reuben

 

Thank your Mr. Wendt and Ms ChickDr19 for your replies.

Here is what I seen in the Repair and Service Manual for the Air Cooler (Turbo) and for the Trans Cooler (all engines). So it appears to me that the engine coolant is used to cool the oil or trans fluid, as applicable. So, I am still somewhat puzzled as to why they would use 210+ degree circulating engine coolant to cool the oil or trans fluid. And, as you see, this is not happening in the radiator. This is happening in their little tiny Dunkin Donuts cooler device.

Pls let me know if I am off-base. Thank you both. Reuben