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Discussion Starter #1
Fuel dilution tends to be very prevalent inside the oil supply of short distance, city driven cars where the oil does not get a chance to reach full operating temperature for at least 10 minutes to burn off excess fuel, moisture etc. For this reason I think it is very important to take the car out for a good 30 or 40 min drive at least once a week, preferably on the highway. It will do wonders to your oil.

If you drive 30 minutes initially to raise oil temps enough and bring the RPM's to about 5000RPM about once a week or so, that's about optimal right there.
 

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Yes, especially in cold climate areas that can be bad issue. reason for that is GDI system. It can cause over fill in oilpan too. To avoid that dilution, it self, are not many tricks.
They say its "normal" that GDI-enignes makes that dilution, but what it do for bearings, camsafts etc. in long time period, not sure. I am little bit conserned for that.
Here is note for this:
 

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Discussion Starter #3
Yes, especially in cold climate areas that can be bad issue. reason for that is GDI system. It can cause over fill in oilpan too. To avoid that dilution, it self, are not many tricks.
They say its "normal" that GDI-enignes makes that dilution, but what it do for bearings, camsafts etc. in long time period, not sure. I am little bit conserned for that.
Here is note for this:
In the worst possible driving conditions, I think that fuel dilution absolutely can be a fairly major issue, and recommending the use of 0w20 oil in north American markets only makes this worse. With thicker oil, the piston rings are able to offer a better seal which mitigates some of the fuel dilution issue. Now, regardless whether you use 0w20 or 10w50 oil, as long as the oil supply has a correct amount of additives, this will ensure the oil supply does not break down further.

The only thing you can really do is just avoid short distance driving as much as you can or at least do a long trip first so that the engine is warm. Cold weather is only going to make this worse.

Just for fun, try smelling the oil on your dipstick after a few short distance trips and then after a good 30-40 minute drive. You will be able to tell the difference.

In the case of worst possible scenarios which cause fuel dilution, I find diesel oil helpful. @bulwnkl also mentioned an oil by the name of Renewable Lube BioSyn which is apparently excellent at managing fuel dilution.

If it is a concern according to your particular driving style, I recommend Motul or Redline racing oils. Expensive but extremely effective.
 

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Discussion Starter #4
I should also add, that in the case of a city driven car, even if it is long distance trips, I would make sure to change the oil frequently, like every 3000miles.

In the case of engine oil which doesnt get a chance to fully warm up whatsoever, it's going to be bad even after 1000 miles.
 

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The only way to KNOW, other than if the oil smells like gas or the vehicle is "making" oil, is to HAVE IT TESTED.

Which isn't that expensive. Sample what you have after a thousand miles, send it in. If you have a severe problem it'll show up.
 

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Discussion Starter #6
The only way to KNOW, other than if the oil smells like gas or the vehicle is "making" oil, is to HAVE IT TESTED.

Which isn't that expensive. Sample what you have after a thousand miles, send it in. If you have a severe problem it'll show up.
The main point of making this thread is to make users try and avoid short distance driving.
 

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In the worst possible driving conditions, I think that fuel dilution absolutely can be a fairly major issue, and recommending the use of 0w20 oil in north American markets only makes this worse. With thicker oil, the piston rings are able to offer a better seal which mitigates some of the fuel dilution issue. Now, regardless whether you use 0w20 or 10w50 oil, as long as the oil supply has a correct amount of additives, this will ensure the oil supply does not break down further.

The only thing you can really do is just avoid short distance driving as much as you can or at least do a long trip first so that the engine is warm. Cold weather is only going to make this worse.

Just for fun, try smelling the oil on your dipstick after a few short distance trips and then after a good 30-40 minute drive. You will be able to tell the difference.

In the case of worst possible scenarios which cause fuel dilution, I find diesel oil helpful. @bulwnkl also mentioned an oil by the name of Renewable Lube BioSyn which is apparently excellent at managing fuel dilution.

If it is a concern according to your particular driving style, I recommend Motul or Redline racing oils. Expensive but extremely effective.
We're barking up this tree again? Oil viscosity thread, v. 600...

Sent from my SM-G960U using Tapatalk
 

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The only way to KNOW, other than if the oil smells like gas or the vehicle is "making" oil, is to HAVE IT TESTED.

Which isn't that expensive. Sample what you have after a thousand miles, send it in. If you have a severe problem it'll show up.
Not all oil analysis Companies provide a direct fuel content measure. I believe with some you need to infer fuel content by viewing viscosity... while also assessing how much viscosity reduction is due to shear...? Others with more knowledge 'bout this pls chime in...
 

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Discussion Starter #11
Not all oil analysis Companies provide a direct fuel content measure. I believe with some you need to infer fuel content by viewing viscosity... while also assessing how much viscosity reduction is due to shear...? Others with more knowledge 'bout this pls chime in...
I believe you are correct. I'm not buying this UOA analysis reports because they all the say the same thing. "metal wear values look good, this looks good, report back in another 5000 miles, blah blah ... blah

Which is basically silly. Drive your car when you need to where you need to.
But beware.

We're barking up this tree again? Oil viscosity thread, v. 600...
No sir. Was just stating thicker oils ability to maintain better piston ring seal. I made sure to specify the thickness of the oil does nothing in terms of oil shearing..

I agree - use it in the manner you need to use it - but be aware. For extreme short trip use a port injected car would be best. Seems to me there are very few left out there.
Yep, pretty much everyone has switched to direct injection. However some brands such as Toyota/Lexus and Hyundai actually use both port and direct injection, depending on your driving style. I guess they were just looking for an easy way to deal with the inherit carbon buildup. DI is most effective while idling or accelerating, especially at higher RPM's, while port injection is most effective during a steady cruise particularly on the highway.

I must mention however; that the inherit design of port injection is still NOT completely fool-proof when it comes to fuel dilution in short distance driving scenarios. Not as bad as DI, but still present.
 

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Not all oil analysis Companies provide a direct fuel content measure. I believe with some you need to infer fuel content by viewing viscosity... while also assessing how much viscosity reduction is due to shear...? Others with more knowledge 'bout this pls chime in...
Which, if you pull a short-time sample, won't come into the picture.

In other words if your usage pattern is mostly short-trip then it's unlikely you will accumulate many miles over a given period of time. So put 1,000 miles on the oil and pull a sample. With modern synthetics you won't find a shear issue, especially in that amount of use, but if there's a dilution problem it's going to show up.

Incidentally I've seen Blackstone (one of the so-called "can't measure dilution" companies) flag samples for dilution and it was indeed right about where they said it was on a confirmatory test. My personal poster child for this was a Yamaha outboard that came back with a number I didn't like, so I pulled a second sample and sent it to a firm that I KNEW did actual fuel testing. THEIR reading was within half a tenth of Blackstone's. That was the end of that debate for me.

There's a lot of competitive puffery out there; HOW you get the result doesn't matter in the end so long as it's accurate.

That people aren't coming up with bad UOAs on these engines is probably due to the engine. I've seen a number of bad reports on different equipment over my years with a couple of that have caught conditions that, had I not known about them, could have been a LOT more expensive than they were (there was a time 10+ years ago when I owned a twin-diesel powered boat where overhauls on those engines had five digits in the price before the decimal if you needed one, so yeah, you want to catch problems well before it goes "boom".)
 

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I just wonder, does every GDI- enigne that dilution or maybe then if you got worn pistonrings. If its leak gas to oilpan and mixed whit oil every time when you get motor run, does that mean
you enigne are not well lubricated since you get right tempature, and what that do to motor with long run.
 

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I just wonder, does every GDI- enigne that dilution or maybe then if you got worn pistonrings. If its leak gas to oilpan and mixed whit oil every time when you get motor run, does that mean
you enigne are not well lubricated since you get right tempature, and what that do to motor with long run.
GDI doesn't "inherently" dilute oil any more than any other design.

Oil dilution occurs when raw fuel gets on the cylinder walls and washes down below the rings. Beyond the direct damage to the lubricating qualities of the oil it also tends to produce abnormally high ring and cylinder wear because it washes the lubricating film off the cylinder.

Properly functioning injectors with an engine running in closed-loop mode have a near-zero amount of excess fuel anywhere, thus nothing to wash down the walls. An engine that produced an excess of fuel when operating properly and did this would also produce insanely high hydrocarbon emissions and fail EPA testing -- and thus couldn't be sold. But that assumes everything is working "as designed."

Injectors that are leaking directly into the cylinder will do so during other than the proper time for injection of fuel and will create a severe fuel dilution problem, but that's a mechanical problem and the correct solution is to replace the bad injector(s). Injectors that are poorly patterning can also create a fuel dilution problem too, as instead of creating a nicely-atomized fuel-air mixture they typically spray liquid fuel which will wash down the walls. Again, the correct solution is to replace the injectors with the damaged or plugged nozzles.

The other issue, and this applies to ALL gasoline engines in the modern era, is that they are programmed to intentionally run rich and expel unburned fuel into the cat during the first few seconds to couple of minutes after a cold start in a bid to "kick off" the cat more-quickly, since closed-loop operation can't happen until the cat lights off. This is done for emissions reasons and normally has no impact on oil quality.

BUT if you do that repeatedly through very short-trip, cold engine operation and never get the engine good and warm you can have trouble from that cause. Quite frankly if that's your operating paradigm you should consider a used (and quite-inexpensive) vehicle like a Nissan Leaf electric; they're pretty cheap on the used market with fairly badly-worn batteries but in that sort of use, plugging it in at home, you'd never notice the horrid range since you simply don't go far enough for it to matter.
 

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Discussion Starter #15
@bulwnkl @Mad Myche @tickerguy @Cdn17Sport6MT

To sum up my view on this whole oil debate, or V. 601 as @DrFeelGood may call it,

I looked at a whole bulletin by Mazda in regards to fuel dilution posted by @RANERANE which mentions that fuel dilution in DI engines occurs because of the excess fuel making its way onto the cylinder walls. Since the piston rings are supposed to stop most of the fuel from mixing into the oil during a piston stroke, you want to limit the amount of blow by caused by your engine. If you experience absolutely zero oil consumption even with 0W20 oil, this indicates an excellent seal of critical engine components such as the piston rings. Now we know that, say a 5w30 weight oil will shear to roughly 5W20 by the engine of its life or even more, this indicates that using an optimal additive blend in your engine oil to fight fuel dilution in your oil supply by using Renewable Lube BioSyn as mentioned by @bulwnkl (Its default oil weight is 5w40, go figure)

Now. An administrator on the CX5 forum I used to follow has an oil catch can on the 2.5 engine and noted almost 500ml of blow by at the end of an interval inside the can. He lives in Texas so he agreed to using 5W30 oil. Well what do you know, his oil catch can was completely empty using 5w30 after the same oil interval.

To conclude, 0W20 doesnt allow for a perfect piston ring seal which worsens fuel dilution further by causing some.blow by, which in turn also leads to slightly more carbon build up on your intake ports.

Coincidentally, another member on that CX5 forum - https://www.mazdas247.com/forum/showthread.php?123864255-Oil-Carbon-build-up-palooza!/page4&p=6586567#post6586567 - Noted a horrific amount of carbon build up on a city driven CX5 2.5 after oil 25000KM. For some reason the pictures on that forum dont show, but I distinctively remember the manifold looking worse than early model BMW twin turbo N54 6 cylinder engines from 2007 which had less build up at 160,000KM..

Now, very rare condition for this engine to have such an issue so I shall assume the engine is under a worst case condition, but its been documented before so still something to consider.

My consensus - stick to a 5W40 oil specifically which is proven to fight against fuel dilution.

Also, here are amazon user reviews. For Motul -


The first review - the guy sent this oil to Blackstone. They said his oil is good for 6000 miles... on a WRX STI. And redline --

 

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Discussion Starter #16 (Edited)
Excellent
GDI doesn't "inherently" dilute oil any more than any other design.

Oil dilution occurs when raw fuel gets on the cylinder walls and washes down below the rings. Beyond the direct damage to the lubricating qualities of the oil it also tends to produce abnormally high ring and cylinder wear because it washes the lubricating film off the cylinder.

Properly functioning injectors with an engine running in closed-loop mode have a near-zero amount of excess fuel anywhere, thus nothing to wash down the walls. An engine that produced an excess of fuel when operating properly and did this would also produce insanely high hydrocarbon emissions and fail EPA testing -- and thus couldn't be sold. But that assumes everything is working "as designed."

Injectors that are leaking directly into the cylinder will do so during other than the proper time for injection of fuel and will create a severe fuel dilution problem, but that's a mechanical problem and the correct solution is to replace the bad injector(s). Injectors that are poorly patterning can also create a fuel dilution problem too, as instead of creating a nicely-atomized fuel-air mixture they typically spray liquid fuel which will wash down the walls. Again, the correct solution is to replace the injectors with the damaged or plugged nozzles.

The other issue, and this applies to ALL gasoline engines in the modern era, is that they are programmed to intentionally run rich and expel unburned fuel into the cat during the first few seconds to couple of minutes after a cold start in a bid to "kick off" the cat more-quickly, since closed-loop operation can't happen until the cat lights off. This is done for emissions reasons and normally has no impact on oil quality.

BUT if you do that repeatedly through very short-trip, cold engine operation and never get the engine good and warm you can have trouble from that cause. Quite frankly if that's your operating paradigm you should consider a used (and quite-inexpensive) vehicle like a Nissan Leaf electric; they're pretty cheap on the used market with fairly badly-worn batteries but in that sort of use, plugging it in at home, you'd never notice the horrid range since you simply don't go far enough for it to matter.
Excellent post. This concludes that good piston rings are essential. In the case of worn rings which allow for even some oil consumption, this somewhat emphasizes fuel dilution, according to your driving pattern. Thicker oil with the right additives will help with this seal, but if the rings are damaged enough no matter how thick the oil in the crankcase is you're still not getting that perfect seal.

However, Mazda seems to use excellent quality internals which means your piston rings should be perfect unless you were abusive to your engine when it was brand new, before the first 5000KM.

So to conclude, @RANERANE , fuel dilution is as potential issue only if your engine never reaches full operating temperature. This indicates that piston ring quality plays a role, but you still need an oil which protects your cylinder walls and piston rings . I wouldn't worry much doing short distance driving in hot weather though.

Theres a reason why highway driven cars often last longer.

@tickerguy lucky you living in Florida. Up north in canada, you need an engine block heater to get the same effect. Those things are great for your engine in the long run.
 

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Fuel Dilution = Fear Mongering.

Follow the manual, meaning use the recommended oil and change when you're supposed to. We're passed the point of stupidity with this subject.

There are Millions upon Millions of DI engines out there. Those that are maintained properly (changing the oil as recommended) do not, have not, suffered from premature engine failure from fuel dilution

Show me one.
 

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Discussion Starter #19
Fuel Dilution = Fear Mongering.

Follow the manual, meaning use the recommended oil and change when you're supposed to. We're passed the point of stupidity with this subject.

There are Millions upon Millions of DI engines out there. Those that are maintained properly (changing the oil as recommended) do not, have not, suffered from premature engine failure from fuel dilution

Show me one.
So Mazda has a whole topic about this inside the owners manual just for fun? I wonder what goes through your head when you decide to post such completely useless posts with zero information on here, consistently.

Yes there are cases of premature engine failure with DI engines. Does it automatically mean fuel dilution is to blame? Its plausible, but difficult to confirm. Does that mean you should disregard the issue whatsoever? No... definitely not.

Many failures are associated with city driving, 0w20 oil, aggressive driving, conveniently failing just outside of warranty period. It all adds up.
 

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So Mazda has a whole topic about this inside the owners manual just for fun? I wonder what goes through your head when you decide to post such completely useless posts with zero information on here, consistently.

Yes there are cases of premature engine failure with DI engines. Does it automatically mean fuel dilution is to blame? Its plausible, but difficult to confirm. Does that mean you should disregard the issue whatsoever? No... definitely not.

Many failures are associated with city driving, 0w20 oil, aggressive driving, conveniently failing just outside of warranty period. It all adds up.
Can you read? Re read my post so I don't have to post it again.

There is no mention of "fuel dilution" in the Manual. It does tell you to follow the scheduled maintenance (schedule 1 - schedule 2) table dictated by your climate and usage and yes, "Repeated short distance driving" is ONE of the many reasons you would follow schedule 2 rather than schedule 1 as per the Mazda manual.

I'll repeat again just for you, Follow the manual, meaning use the recommended schedule you're supposed to based on you driving habits and climate.

And no, it doesn't all add up. Where do you come up with this stuff? The BMW forums?
 
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