About to leave for big roadtrip!

Technically no. I inquired to this tech I talked to about the fluid a few weeks ago. He said they have cars coming in with 100k+ and the transmission fluid is stark black and thinner(it should be blue), they called Mazda on it and Mazda was adamant that the fluid doesn't break down and doesn't need changing(well, obviously it does since the fluid has changed colour and viscosity!). I know when mine reaches 60k, I'll be doing a drain and refill of ATF.

Seriously? It doesn't break down? Now...I would believe them if they said "the transmission is engineered as such that any break down of the fluid that will occur, will not adversely affect it." But...seriously...does NOT break down? Jeez.

I'm tempted not to. Just because my dealer doesn't recall ever doing that fluid change. Seems to me the trans should go 200 thousand miles at least on oem fluid. I know plenty of vehicles that have.
 
It's common knowledge that all cars do this that have modern ECU. The cx5 sith a 13 to 1 comp ratio is especially aggressive. No link is necessary, imo, as this falls under "the sky is blue" territory.

I suspect you Re correct, but I caution that usually when everyone just knows something, they are wrong. This case MAY be an exception.
 
I suspect you Re correct, but I caution that usually when everyone just knows something, they are wrong. This case MAY be an exception.

Modern vehicles are a bastion to efficiency. The more timing you can run, the more efficiently you are running, typically. But run too much timing, and you get detonation. Modern vehicles have tons of sensors that predict and actually listen for pre-detonation. Typically, a vehicle advances timing until either a set point, or it senses this, then backs off safely. On hotter days, safe is less, under load, too, etc. Even on simple OBDI era vehicles, this formula was followed pretty well. I think the king of all of it was the 1989-1993 Mustang GT. You could literally do ANYTHING to those motors and they didn't need a tune unless you went FI or stroked it to 347. A solid dynotune would only net 5-10whp gain on them, they were so efficient at correcting for environmental and operational parameters. I wish all vehicles were that adaptive.
 
Quote Originally Posted by Unobtanium View Post
It's common knowledge that all cars do this that have modern ECU. The cx5 sith a 13 to 1 comp ratio is especially aggressive. No link is necessary, imo, as this falls under "the sky is blue" territory.

I suspect you [a]Re (sic) correct, but I caution that usually when everyone just knows something, they are wrong. This case MAY be an exception.


There are FAR too many variables here to make such a blanket statement. How much load? How hot is hot? Hot coolant or hot air?

Octane Rating
You'll note that "octane rating" is a mark of chemical stability and has nothing to do with cooling or energy content. And also that pistons have no bearing on ignition timing, plus, that the spark occurs BEFORE the piston reaches Top Dead Center on the compression stroke, not after.

Uber Cool Video

octanegraph.jpg


papers.sae.org
1989 SAE paper documents the reduction in octane demand at altitude. Click "View" on the right side.
A reduction in octane demand (requirement) at altitude negates any need to "pull timing". (deadhorse

car and driver/regular-or-premium
Not all engines gain power on Premium.

Still, I'm mystified by most of this discussion. So much guessing and so much concern about the ECU doing the correct thing to maximize power or fuel mileage for the situation presented and there is nothing we can/should do about it.
 
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There are FAR too many variables here to make such a blanket statement. How much load? How hot is hot? Hot coolant or hot air?

Octane Rating
You'll note that "octane rating" is a mark of chemical stability and has nothing to do with cooling or energy content. And also that pistons have no bearing on ignition timing, plus, that the spark occurs BEFORE the piston reaches Top Dead Center on the compression stroke, not after.

Uber Cool Video

octanegraph.jpg


papers.sae.org
1989 SAE paper documents the reduction in octane demand at altitude. Click "View" on the right side.
A reduction in octane demand (requirement) at altitude negates any need to "pull timing". (deadhorse

car and driver/regular-or-premium
Not all engines gain power on Premium.

Still, I'm mystified by most of this discussion. So much guessing and so much concern about the ECU doing the correct thing to maximize power or fuel mileage for the situation presented and there is nothing we can/should do about it.

OP was towing a trailer heavier than their vehicle was rated for, up a mountain. I kindof presumed a "bad case scenario" there, and reasonably so, I think...
 
OP was towing a trailer heavier than their vehicle was rated for, up a mountain. I kindof presumed a "bad case scenario" there, and reasonably so, I think...

From the OP in Vancouver we're meeting up with my uncle who has a 2,000lb(dry) camper trailer, he asked if we could tow his trailer on a 1 hour drive to a campsite. The roads going there will be flat and slower speeds(50mph).
 
There are FAR too many variables here to make such a blanket statement. How much load? How hot is hot? Hot coolant or hot air?

car and driver/regular-or-premium
Not all engines gain power on Premium.

Still, I'm mystified by most of this discussion. So much guessing and so much concern about the ECU doing the correct thing to maximize power or fuel mileage for the situation presented and there is nothing we can/should do about it.

The car and driver article contains this, But, noted Schiller, only a few vehicles calibrated for regular fuel can advance timing beyond their nominal ideal setting when burning premium. BUT it was written in 2001, so we have more info, but not more answers. We still don't know if premium fuel helps. I do know my car runs just fine on regular while pulling a (small (1000 lb)) trailer on hills in 89f deg heat.
 
The car and driver article contains this, But, noted Schiller, only a few vehicles calibrated for regular fuel can advance timing beyond their nominal ideal setting when burning premium. BUT it was written in 2001, so we have more info, but not more answers. We still don't know if premium fuel helps. I do know my car runs just fine on regular while pulling a (small (1000 lb)) trailer on hills in 89f deg heat.

Correct, but there is no need or logic in designing an engine to run on 87 octane, while including the capacity to also run optimally on 93 octane. Having said that, I have read that Ford's Coyote Mustang 5 liter V-8 has a setting activated by the ignition key to switch octane and get, I think, 14 more HP.

I can't feel any difference in mine on premium. I can see about a 10% increase in mileage if I run gasoline that is not contaminated by ethanol.

BTW, on a completely different subject, ethanol belongs in charred oak barrels, not gas tanks!!!!!! (thumb)
 
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BTW, on a completely different subject, ethanol belongs in charred oak barrels, not gas tanks!!!!!! (thumb)

Best entry in the Mazda CX-5 forum this month. That might be a new sig line.


"Ethanol belongs in charred oak barrels, not gas tanks"​
ColtX-5
 
BTW, on a completely different subject, ethanol belongs in charred oak barrels, not gas tanks!!!!!! (thumb)
Best entry in the Mazda CX-5 forum this month. That might be a new sig line.
"Ethanol belongs in charred oak barrels, not gas tanks"​
ColtX-5
Totally agree!

Especially corn-produced ethanol! Doesn't make any sense!
 
Nearly done our trip. We're 1/4 way home(Kamloops) from Vancouver. We did three fill ups with 91 octane shell v power. Then did a few tanks of 87 shell fuel. No difference in fuel economy or power. I could MAYBE feel a difference in low end grunt, but hardly noticeable. ALSO: We went up from Vancouver to Kamloops on highway 5(the coquihala aka: highway thru hell). Climbs 4,200 feet over 200km(130miles). Speed limit is 120km/h(75mph) and I did about 90mph up the whole way. A couple times I hit 120 for extended periods. Not once did anyone pass me. I absolutely loved it! That highway is 3 lanes nearly the whole time, and is totally built for these high speeds. Plus there was hardly any traffic so I had a burst of testosterone and did 130 miles in just over an hour. There were lots of corners and the CX-5 handled like a German SUV. It reminded me of a BMW X3.

Never was the CX-5 lacking in power, it held 100mph with cruise set(albeit, it was in 4th gear doing 5,000+ rpm) doing 8% grades with about 850 pounds of people and cargo, using 87 octane, with A/C on, in 35 degree heat. And you know what the fuel economy of this high speed, uphill stint over the 130 miles? 24mpg!!!! How the hell did it do so well at these speeds and still get that good of fuel economy? Because boy, I was driving the piss out of it! Count me impressed! Btw: yes I did do an idle cool down for a few minutes when I parked it. Also, another note on fuel economy, driving around Vancouver area and Vancouver island, I was getting a consistent 34mpg in HOT weather with A/C never off. It seems that the hotter it is, the better these cars perform. What a great little SUV.
 
Nearly done our trip. We're 1/4 way home(Kamloops) from Vancouver. We did three fill ups with 91 octane shell v power. Then did a few tanks of 87 shell fuel. No difference in fuel economy or power. I could MAYBE feel a difference in low end grunt, but hardly noticeable. ALSO: We went up from Vancouver to Kamloops on highway 5(the coquihala aka: highway thru hell). Climbs 4,200 feet over 200km(130miles). Speed limit is 120km/h(75mph) and I did about 90mph up the whole way. A couple times I hit 120 for extended periods. Not once did anyone pass me. I absolutely loved it! That highway is 3 lanes nearly the whole time, and is totally built for these high speeds. Plus there was hardly any traffic so I had a burst of testosterone and did 130 miles in just over an hour. There were lots of corners and the CX-5 handled like a German SUV. It reminded me of a BMW X3.

Never was the CX-5 lacking in power, it held 100mph with cruise set(albeit, it was in 4th gear doing 5,000+ rpm) doing 8% grades with about 850 pounds of people and cargo, using 87 octane, with A/C on, in 35 degree heat. And you know what the fuel economy of this high speed, uphill stint over the 130 miles? 24mpg!!!! How the hell did it do so well at these speeds and still get that good of fuel economy? Because boy, I was driving the piss out of it! Count me impressed! Btw: yes I did do an idle cool down for a few minutes when I parked it. Also, another note on fuel economy, driving around Vancouver area and Vancouver island, I was getting a consistent 34mpg in HOT weather with A/C never off. It seems that the hotter it is, the better these cars perform. What a great little SUV.

Wow! I averaged something like 22mpg on flat ground doing 85 on a trip to south louisiana last year.
 
I don't know why but hills don't seem to reduce mileage much, may improve it.
 
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