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If memory serves - it is 75W-80... but most importantly it is GL-4. You cannot use GL-5. Some of us don't like MT1 buffered GL-5 for that matter. I think I have this right...
 

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Correct -- NEVER run any MTX that is labeled for GL-4 with ANY oil that has a GL-5 rating anywhere, through any means, ever.

It will destroy the synchros; the problem is that GL-5 lubricants have a film strength that exceeds that of the material the synchros are made out of and thus the synchros shear instead of the oil!

Redline MTL is available in 75w80, which is the correct viscosity for these gearboxes and in my experience it produces materially less notchiness, especially when the gearbox is cold, than the factory fill. I've had it in my car since about ~40,000 miles, am now approaching 190k, and have continued to use it -- I've seen no reason to change away from it.
 

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Discussion Starter #5
I'm contemplating on using 75W90 and 5W30 for the engine oil. I like to shift at 3-4k RPM. From what I understand, 75W80 is a fuel efficient alternative to 75W90, and 0w20 is recommended because of CAFE standards (fuel economy) in the U.S. The rest of the world uses 5W30. The manual even indicates it. I live in Florida and do not deal with cold weather. Thoughts?
 

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I see no reason to do either.

I have UOAs from my engine that say there's absolutely ZERO benefit to switching off 0w20. In addition I see no benefit in doing it with the gear oil either.

If you ever DO travel where it's cold you are you're likely to be quite unhappy with the thicker MTX oil when the car is cold.

I suspect the real reason for the 5w30 being used in other parts of the world is that 0w20 is hard to obtain, particularly away from major urban areas, where it's extremely common here in the United States everywhere. You can get 0w20 at any WalMart anywhere in the US, so that's not a factor here.

There are also fuel quality differences between nations, specifically in the amount of sulfur allowed. Mexico's sulfur annual average limit is three times ours (30ppm .vs. 10ppm) although their absolute maximum on a single run is comparable.

If I had any indication that using 0w20, even living in a hot climate (I'm in Florida) was insufficient, I'd have changed long ago. There's no indication of that at all and as a result there's no reason to do it. I happen to prefer Pennzoil Pure Platinum 0w20, but that's simply because at this point I have nearly 190,000 miles of service record on that oil in this engine and see no reason, absent a loss of convenient supply of it given its attractive price-point and availability, to change. The same is true for my '03 Jetta TDI; that engine has about 280,000 miles on it, all of it on Rotella T6 since the factory fill came out of it over 15 years ago, and the last time I had the rocker cover off to do the timing belt the cam was in very good condition for an engine that has a quarter-million miles on it, remaining perfectly serviceable.
 

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Discussion Starter #7
I was using Pennzoil Ultra in my Focus, but I just ordered Redline 0W20. I had a 2017 Focus and it ran beautifully on Shell Nitro+ 93 octane. Have you tried this in the Mazda 6?
 

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Yes, but it's hideously expensive in this part of the country compared against regular fuel, and not worth it. I have an OVTune file for Premium fuel as well, but I think I've used it once or twice. I simply refuse to pay the crazy premium for the fuel over Regular 87 octane.

Incidentally when traveling in the mountains (e.g. Colorado) Regular is 85. Not only does the car run perfectly well on that the fuel economy goes UP by a couple MPG!
 

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Discussion Starter #9
Premium burns hotter, cleaner, and if the computer adapts it should give more power at the cost of fuel economy. Also, the additive package will help prevent the carbon that I've read this Skyactiv engine can have. It's not much more for Premium here in Gainesville.
 

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Whereas a direct injection engine (without additional port injectors) can theoretically have issues with intake valve build-up (and indeed, all such engines DO create some deposits on the back-sides of the intake valves) the SkyActiv engines certainly appear to NOT have problems. Injection timings, multiple injection events, and the temperature the intake valves are allowed to get to apparently all play a role in whether the buildup is a little (and not problematic) or a lot. Mazda appears to have been getting the formula right.

I can't see how ANY motor-fuel formulation could affect whether buildup is a little or a lot (as only air + oily crankcase air / fumes) makes its way past the back-sides of the valves. Never fuel-laden air with aerosol droplets of high detergent additive fuel.

Oh, and though the logic module / knock sensor(s) can trim-back on advance (and hence lower power level) in response to lousier than expected, lower than AKI 87 fuel - for whatever reason this SkyActiv engine (in stock form) appears to NOT be able to pull MORE HP / torque out of higher octane fuels. I don't know why...
 

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Discussion Starter #11
That's interesting, because the manual recommends a minimum of 87, indicating you can go higher. That's unfortunate if 93 performs worse. It can take a couple of tanks for the ECU to fully adjust, however I know that the compression ratio is different in the U.S. at 13:1 instead of 14:1 in Europe. Maybe that was to accommodate the regular unleaded fuel.

This engine is pretty amazing. When you step on the gas, it has an awesome and unique sound that let's you know you're in a Mazda! I love this Gen 3 model so far.
 

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Premium burns hotter, cleaner, and if the computer adapts it should give more power at the cost of fuel economy. Also, the additive package will help prevent the carbon that I've read this Skyactiv engine can have. It's not much more for Premium here in Gainesville.
You almost got one point correct, and that is about more power.


The Octane Rating is the resistance to ignition.
What this does is allow for higher compression and/or more ignition timing. Either of these allow for a more efficient burn which results in a combination of fuel efficiency and performance; dependent upon both the "tune" of the car and how you drive the car.



Hotter/Cleaner: Not on it's own. Then engine may run hotter and there may be less emissions; but that is dependent upon again on the driver and the state of tune.


Additive package will help prevent the carbon...: That has nothing to with octane. That is all on the oil company and what they add into the fuel. There could actually be a smaller additive package with less cleaners in the fuel; the only additive requirements are minimums which do not vary by grade. Most of the major US oil companies sell Top Tier licensed fuels which has a larger additive package than regulations require.



...the carbon that I've read this Skyactiv engine can have: All engines can have carbon deposits; and (especially the early) Direct Injection engines are prone to higher levels as they are not being washed off by fuel coming through the intake valve.
The SkyActiv engine is a DI engine which is less prone than other DI engines to deposits, and there has been no substantial evidence to say otherwise. As it is a true Direct Injection engine, which has zero fuel flowing through the intake and valves, the additive mixture cannot clean the valves regardless of quantity.
 

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Discussion Starter #13
I like to shift between 3-5k RPM, with heavy acceleration. I also do lots of highway driving at 80mph+ which keeps this engine around 3k RPM.

Do you recommend a certain tune to be able to utilize 93 octane that will not cause a check engine light?
 

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I like to shift between 3-5k RPM, with heavy acceleration. I also do lots of highway driving at 80mph+ which keeps this engine around 3k RPM.

Do you recommend a certain tune to be able to utilize 93 octane that will not cause a check engine light?
I've never gotten a check engine light on my SkyActiv and it is OVTuned. As I pointed out I have both files for 87 octane and 93, but I basically never run the 93 as it provides very little additional torque or horsepower but does drain my wallet significantly faster at the gas pump.

Is there a SMALL improvement in smoothness of operation on 93? Yes. The ECU is dynamically managing timing and valve overlap on 87 and if you're one of those people who are very aware of their car (I am) you can feel it. There's materially less of that on 93. But -- while the torque and horsepower curves I have for 93 ARE very slightly higher than on the 87 file the words very slightly are the operative ones here.

The torque lift down in the lower part of the RPM band from the OVTune in the first place, however, is IMHO well worth it. In terms of raw horsepower improvement it's not all that impressive, but the driveability improvement from lifting the torque band in the lower RPM range is very material and it requires no instrumentation to know it's there. How much this would matter if you have the ATX is a different story; a torque converter can cover a lot of low-RPM sins when it comes to engine torque curves, but of course an MTX doesn't have one of those.

Your fuel economy suffers mightily at 80mph; even tuned the "knee point" where the engine appears to come out of the "pseudo Atkinson" cycle due to required output is right around 73mph or so; there is a LARGE difference (2-3mpg!) that's basically a step function right there in 6th gear and of course with exponentially-increasing wind resistance it only gets worse, and fast, from that point onward.
 

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Discussion Starter #15
I tried looking for the OVTune but it looks like they only work on Toyota now. Does anybody have a link or part number?

Also, can anybody explain why 93 octane is recommended in the summer?
 

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Discussion Starter #18
Thank you for the link. The recommendation for premium in the summer is in the manual for my 2017 Focus, and my father's 2014 Lincoln. I know those are both Fords, but there has to be a reason they recommend it in hot weather.
 

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Ford & Lincoln's owner manual recommendations or the Duratech engines really are not germane to a Mazda 6 with a SkyActiv engine.


But, the first thing I am thinking is yes, they will geta little more performance/economy on premium. You may not feel or see it; but when it comes to the tax man collection CAFE money that 0.1% fuel economy increase means a lot less money they have to pay for not meeting the requirements.
Slight improvements in fuel economy is also the reason that Ford has been selling the Focus & Fiesta with transmissions that were known to be faulty prior to them being released.
 
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