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Discussion Starter #1
I have done about 5 oil changes on my car and it has 20K. I have another car with a 2.5L and it only requires 4 quarts but the 3.0L requires 6 quarts. I was just wondering why does Mazda requires so many quarts of oil for the 3.0 L. My opinion is that since the oil change interval is 7500 miles they need that much oil so the car can make it that far before the oil gets to dirty. Somebody out there tell me if im wrong or right.
 

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Oil is used for engine cooling as well, so helps in the cooling process. And, oil amount is not contingent on engine size either. I have a jeep grand cherokee with the 4.0 inline6 and it takes 6 quarts also. Just depends on the size of the oil pan for cooling reasons
 

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More oil capacity = more fluid volume for heat to dissipate. Could also mean that you installed oil cooled twin turbos in place of your exhaust on your C5 corvette and you had to account for the extra fluid in the turbos and lines. :yesnod:

This does not mean its ok to put 7 quarts into an engine specified for 6 quarts.
 

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It has more cause they designed the engine that way. It's not a bad things except it costs more to do an oil change, but it means the engine is safer. Don't sweat it and just make sure to fill her up.

And no, it doesn't have a damn thing to do with oil change frequency.
 

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Discussion Starter #6
It has more cause they designed the engine that way. It's not a bad things except it costs more to do an oil change, but it means the engine is safer. Don't sweat it and just make sure to fill her up.

And no, it doesn't have a damn thing to do with oil change frequency.
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So if it doesnt have anything to do with the oil change frequency what allows mazda to space out there oil changes much futher apart than the always recommended 6month/3000 miles?
 

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It's 3 month, 3000 miles, but that is only because they can. If you car is synthetic, that could be part of it (BMW reccomends 15000 miles), but keep in mind that overy 5000 miles is acceptable depending on your driving style
 

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Don't forget, oil also removes combustion contaminants that aren't blown out of the exhaust. The more oil, the more of those contaminants - the main enemy of synthetic oils - your oil can absorb without losing it's lube ability.

6 quarts makes the synthetic oils last longer than if you only needed 4 quarts.
 

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The volume of the 6s oiling system is a byproduct of years of refining the pan design to try and resolve a variety of oil starvation issues in high g cornering situations.

The 3.0 duratec has an oil pump that runs on a 1/1 ratio. It turns with the crank. Most engines have a pump that turns one revolution for every 2 crank revolutions. Not the v6 in the 6s.

Originally there were some oil return issues on 2.5 duratec's. The oil couldn't return to the pan fast enough, and under certain situations (right hand sweepers at near redline), there would be oil starvation.

Since then there has been so many changes and refinements since then it's almost impossible to count. The end summary is that the oil passages have been changed multiple times, the baffling/windage/pan design at least 7-8 times (twice since the 03 mazda6). Along with these changes oil capacity has risen, as it provides both cooling benefits, and reliability/longevity benefits in addition to protecting against oil starvation.

If you check the older engines (like the 4 qt 2.5 v6), you'll notice that the oil change interval's are also spec'd much shorter. It's pretty hard to run a 7500+ OCI when you have a small volume of oil to deal with.
 

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Speaking of oil...

I just shift to Castol Syntec 5W-20 for the first time (Mobile 1 before) and the engine feels a lot more responsive. :drive: Don't know if the mpg figures will change though.

Is the oil really making a difference or is it all in my mind :(
 

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Yet my old Nova had a 3.5 quart capacity and a 10,000 mile drain interval (not that we EVER took it nearly that long... the oil was dirty at 2000 miles!)
 

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The 3.0 duratec has an oil pump that runs on a 1/1 ratio. It turns with the crank. Most engines have a pump that turns one revolution for every 2 crank revolutions. Not the v6 in the 6s.
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shouldn't this be a good thing? or is it that the pump is not getting enough oil to pump because of this?
 

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It's probably the placebo effect from changing your oil.
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not a placebo effect.

The effect is for real. New oil = better lubrication. No?

he would have gotten the same effect if he had gotten the Mobil1.


but, the one time I REALLY found the engine to run smoother was when I swtiched to Redline Synthetic transmission oil (after only 1000 miles). The gears in the gearbox just slid like there was no friction.
 

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The effect is for real. New oil = better lubrication. No?[/b]
Not really. Most people change their oil (especially synthetic), far before the oil's additive packs have actually depleted to a level that would effect the oil's performance. The oil might look dirty, but its not going to perform at a noticably worse level then the oil you're replacing it with.

I've actually seen some bob guys drain their oil out, install whatever mods they needed to, then reuse the oil they drained because the TBN was well within the green range.

Janice changed her oil at 7,700 miles, and the UOA indicates she could have easily gone 9,000+. Remember that color and smell are not indiciative of the amount of wear on an oil.
 

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Discussion Starter #17
I cant imagine that switching from one brand of synthetic oil to another would create a noticable difference. It seems to me that unless you raace your car and are constantly bouncing it off the redline that your brand of oil shouldnt make any noticable differences. There are just to many other power losses throughout the engine that play into the responseivness of the engine. Does changing just one of these variables affect the engine that much. This is just my opinion though what does everyone else think out there.
 

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I have done about 5 oil changes on my car and it has 20K. I have another car with a 2.5L and it only requires 4 quarts but the 3.0L requires 6 quarts. I was just wondering why does Mazda requires so many quarts of oil for the 3.0 L. My opinion is that since the oil change interval is 7500 miles they need that much oil so the car can make it that far before the oil gets to dirty. Somebody out there tell me if im wrong or right.
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The 2.3L turbo in my MS6 takes 5.7 liters... so 6 quarts for a 3.0L sounds in line
 
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