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Thought I would share my experience switching from the Castrol 0W20 to Liqui-Moly 5W30. The engine felt more smooth, sounded much more quiet and healthy especially with the hood up - It took me by surprise. Oil consumption has dropped from 1L every 9000KM to 1L every 15,000+KM. Note that in the rest of the world the following oils are approved:

5W30
5W40
10W30
10W40
10W50

There is nothing wrong with using the approved, FAR more proven 5/10W oils for this engine, especially considering that 0w20 has been around for merely 5 years and has absolutely zero track record as being reliable in high mileage situations. This engine is clearly built around very high performance as the max 10W50 oil weight approval may suggest. According to my mistake, the oil pan can hold at least a quart of oil past it's recommended fill level with zero issues for an extended period of time. This means our engine has a very aggressive and high-performance oil-pan that ensures the engine is not starved of oil during full throttle high speed corners. All of this makes it clear that we are dealing with a high-performance engine designed around upwards of 10W50.

Let me just make one point before I hear "modern tolerances" again. The Mazda NA 2.5L, code-named PY-VPS is a modified evolution of the previous generation L5-VE 2.5L engine. This Skyactiv motor is NOT a clean-sheet design. Both engines have identical Bore X Stroke dimensions and overall displacement. This means that the internal-tolerances are NOT modern. Do you seriously believe that 10W50 and 0W20 have the same amount of protection in hot-weather? Please refer to this picture here, an oil temperature chart from Mazda before the CAFE shit:

As you can see, even 5W20 is only good for very cold weather, let alone a 0W. Thick oil and thin oil Obviously does not protect the same in hot weather. Now go back to what CAFE intends to do. It stands for Corporate Average Fuel Economy, a program made by the government to lower emissions and increasing fuel economy by using oil with less friction. Each car gains a roughly 0.2 MPG increase in fuel economy, which when added up results in big tax credits/savings for manufacturers who choose to follow CAFE's requirements. Do you want a 0.2MPG increase in fuel economy or increased long-term engine protection? The choice is yours.

5w30, 5w40 oil, with the right additives included, helps to protect your engine from fuel dilution, which breaks down your engines oil supply because of the way direct injection works and all the sulfur in our fuel. This is a very important reason to always change your oil often, especially if you do lots of short distance city driving.

Another reason is carbon build-up on the intake valves which is a known issue with DI motors. It does not happen much with these motors, but there are recorded instances. According to Chris_Top_Her, a moderator over at Mazdas247 his oil catch can caught significantly less blow-by when using 5w30 VS. 0w20. This means that the thicker oil reduces the production of carbon build-up in your engines, particularly on the intake valves:
(https://www.mazdas247.com/forum/showthread.php?123864255-Oil-Carbon-build-up-palooza!)

Your engine is designed to run at the same temperature year-round, regardless of how hot it is outside. However, if you like to drive aggressively, especially in hot weather where your engine-bay is more prone to heat soak, oil temperatures will inevitably rise. Thicker oil such as 5W40 helps maintain a thicker layer between the moving metal parts in your engine, thus reducing friction and increasing engine longevity. Bottom line, just use an oil weight appropriate for the ambient conditions you drive in and the way you drive. BMW M engines all use 10W60 oil which is not far off from the 2.5L's maximum oil weight of 10W50, meaning you got lots of room to choose an oil weight best suited to your driving style and conditions. All engines will inherently burn oil quicker with 0W20 since it is so thin, but using a thicker weight will likely stop oil consumption all together or at least noticeably decrease it.

Yes you can use 0W20. But unless you have perfect metal-wear ratings or plan to sell the car early there is a whole plethora of reasons why you shouldn't.
 

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This is wrong on a whole host of points, but I took the others on in your other screeds.

I'll take the CI-rated oil one on here.

Diesel-rated oils have a different additive package because diesels produce SOOT as an inherent part of their operation. Gas engines do not to any material degree. A diesel-rated oil thus must suspend this soot for the change interval (the particles are too small to be filtered by standard full-flow filters; this is why diesel oil turns black almost instantly after being put into service) and this demands a different additive package.

In addition prior to ULSD being mandatory diesels also used to produce a lot of sulfuric acid by their nature; sulfur in the fuel combined with water vapor in the air to produce H2SO4, which of course is Sulfuric acid. Therefore diesel-rated oils tended to have a quite-high TBN so they had enough buffering capacity to neutralize that acid over the service life of the oil; running out of TBN would result in acid etching of bearing surfaces and premature engine failures. This is much less of an issue today with ULSD, and in addition most of the TBN-spiking elements used in older diesel oils are SCR poisons, so they must be limited due to the use of SCRs for exhaust after-treatment in modern diesel engines.

A diesel-rated oil is ok to use in a gas engine if and only if it also carries the proper SI (spark ignition) rating. Some do, and some don't. The requirements between CI and SI engines are DIFFERENT; in the general case it's NOT a good idea to run a diesel oil in a gas car, and it's usually catastrophically bad to run a gasoline engine oil in a diesel vehicle.

Rotella T, incidentally, is an excellent diesel-rated oil that I have run for over 230,000 miles in my '03 Jetta; I recently did the timing belt which required removing the valve cover and even with over 200,000 miles on the clock the cam lobes looked excellent. Consumption on that engine is modest; it typically goes through about a quart and thus wants a bit of a top-off during a service interval, which for an engine with 200,000 miles on it is quite good. That oil, however, will never see the inside of my Mazda's crankcase, however, as it is flatly-inappropriate to use in that vehicle.

My '15 Mazda has over 100,000 miles on it and consumes about 1/3rd of a quart of oil over a 7,500 mile service interval, and UOA shows near-zero wear metal presence and no fuel dilution over said time and mileage in-service. It has run 0w20 oil exclusively, I live in the nice hot Florida climate, and the two oils that are both inexpensive and readily available here are Mobil 1 0w20 "European" and Pennzoil "Pure" 0w20, both synthetics. I choose based on which is cheaper at any given time and have seen no difference in either consumption or wear metal presence between them. In fact I am approaching my usual 7,500 mile interval now and just bought a 5qt jug as I will be changing the oil again within the next full tank of fuel burned.
 

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5w40 is the WRONG viscosity grade in these engines.

5w30 is recommended for Skyactiv engines in Mexico, incidentally. If you live where you never see temperatures under freezing then it likely meets requirements. However, cold-start lubrication during lower temperatures will be severely impaired by using a 5w30 and this will materially increase engine wear, so if you live where temperatures EVER go below 0C it's foolish to do so.

There is utterly no problem with 0w20 oils even in extremely hot climates. I live in Florida where summer temperatures regularly exceed 100F and have zero evidence of any sort of wear issue in the quite-severe service that my engine sees on a temperature and load basis.
 

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0w20 is the last oil weight you would want to put into your car living in Florida. Seriously.

0w is only useful for -20c weather or lower. Use 0w30 in the winter (only if you park outdoors or it is very cold) otherwise 5w30 won?t wear out your engine any more then 0w20.

In the summer, 5w30 should be used. Mexico isn?t the only place in the world that uses 5w30. Hell, even Russia which is more cold then Canada during the winter still uses 5w30 oil! It?s not that bad for cold starts (unless you park outside)

Either way, this engine was designed around 5w30 originally meaning that this weight will fill the bearings better and provide More protection once the engine is warmed up.
How much "more" protection can you get than the DOCUMENTED results from the multiple UOAs that I have right here? Zero is zero, and these results are statistically indistinguishable from ZERO when it comes to wear metal presence in the oil after it has gone through an entire service cycle.

Look dude, you have spammed this forum with a whole host of repeated bald assertions, bereft of ANY evidence to back it up. I have hard, scientific evidence that says you're WRONG in your assertions, and that evidence has thus far produced wear metal levels that are lower than ANY I have ever seen on ANY engine I have EVER owned over roughly 40 YEARS of driving, never mind off-road engines (e.g. marine, etc.)

All of this was produced EXCLUSIVELY on 0w20 oil in this engine, and it's a scientific FACT.
 

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How much "more" protection can you get than the DOCUMENTED results from the multiple UOAs that I have right here? Zero is zero, and these results are statistically indistinguishable from ZERO when it comes to wear metal presence in the oil after it has gone through an entire service cycle.

Look dude, you have spammed this forum with a whole host of repeated bald assertions, bereft of ANY evidence to back it up. I have hard, scientific evidence that says you're WRONG in your assertions, and that evidence has thus far produced wear metal levels that are lower than ANY I have ever seen on ANY engine I have EVER owned over roughly 40 YEARS of driving, never mind off-road engines (e.g. marine, etc.)

All of this was produced EXCLUSIVELY on 0w20 oil in this engine, and it's a scientific FACT.
Thanks Ticker. Some of the just wrong information that gets tossed around gets so annoying on here.
 

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Wrong information? Have you bothered to look up the cafe requirements and actually understand why the government wants you to use thinner oil in the first place? Oil that is thinner then what the clearances in our engines want?

Or areyou too focused on the fact I?m trying to deviate away from a government scam to realize that maybe 5w30 is a better choice? because this is what the rest of the world has been safely using for far longer then any 0w has been around...

You guys all sound naive, ignorant and totally unwilling to do any sort of basic research. This forum is terrible for sharing or having any sort of meaningful conversations
I actually find it (this website) quite good for gathering, discussing, and trading information and ideas. You should try these arguments somewhere like MazdaSpeedFourm or Rx7/8 world - you'd get quite the earful.

The problem I see in these arguments presented is that one side is providing factual real-world evidence to prove that their side is correct while the other is blaming government conspiracy.
 

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All I can say is that if the engine ever busts a nut using the wrong oil, good luck with your warranty claim. Automakers do a lot of research into what viscosity works best. To go that far outside their recommendation would definitely void the warranty for an engine failure.
 

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I'm well-aware of the CAFE issue.

However, that doesn't change the facts when it comes to engineered clearances in a given engine, what oil they're optimized for, and the documented, scientific results obtained by following said manufacturer recommendation over an extended period of time -- in this case, over 100,000 miles of in-service use.

Yes, my numbers are from ONE engine. However, I only own ONE engine and the fact of the matter is that there is no statistically-material improvement in wear rates possible from the results I'm obtaining using said recommended weight oil.

Further, while you may claim the CAFE is a "conspiracy" game the fact is that I benefit from better fuel economy as well since I travel further while spending less money. If that can be had without compromising engine life I'll take it and IMHO you should too.

In my my case if the difference is 1 mpg (which it might or might not be), given my fuelly profile and average mpg (and average per-gallon gas price) over the car's life that amounts to $253 that is in my pocket instead of the "evil oil company" bank account since I bought this vehicle as a direct result of using the more fuel-efficient oil.

You may consider $253 to be immaterial to you. I look at it as glasses of beer that I can drink instead of putting into my tank in the form of gasoline, and that's quite a few glasses of said beer.
 

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if you live in a hot climate and/or drive aggressively, do you agree that this $200 figure is best spent toward added engine protection?
I live in a hot climate (Florida), drive aggressively (all the time) and why would I spend the $253 on nothing?

Again, I have documented proof that in my drive cycle and environment THERE IS NO GAIN IN WEAR RATES TO BE HAD BY RUNNING A HIGHER VISCOSITY OIL.
you can also agree that a thicker oil provides a better coating over critical engine parts which results in more protection, correct? I think this is critical depending on some driving situations.
No, I DO NOT agree with that claim, and in fact I know it is false.

Either the oil film in sleeve bearings (e.g. mains, cam bearings, etc) is of sufficient strength to prevent metal-to-metal contact or it is not. If it is then more is not better; it does nothing to reduce wear rates but does increase frictional energy losses, which means LOWER thermodynamic efficiency (in other words, less fuel economy.)

HOWEVER, thicker oil flows more-slowly on start-up. It is those critical seconds that have been PROVED to cause most engine wear. This is why large industrial engines often have powered pre-lube systems so the oil system is under full pressure before the crank turns. Running a thicker oil means that full pressure at the bearings will be achieved SLOWER, and this may well cause HIGHER wear rates rather than lower ones.
I will say, that I have used 0w20 in this car for a while before switching to 5w30 and the difference was significant.
I'm assuming you have UOAs for wear metals both with 0w20 and 5w30 to back this claim up? If so, where are they?
 

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Look, we hear what you're trying to say and in theory it sounds logical. However, some members like tickerguy have over 100,000 miles UAO's (Science) to backup their claims. I would add as far as the power or smoothness, I would agree that it's a stretch to say you can feel the difference between 0W-20 & 5W-30. I live in Houston and have been using 5W-20 and now 0W-20 in Honda's and now Mazda's since 2004 with no issues.
 

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Here in Vegas on other engines, I've used 0W-30 and had no issues at all. It gets pretty hot so that 30W side of the equation can help. But on the other hand it gets cold for a couple months or so as well, so that 0 figure is nice. I wouldn't expect the engine to have any issue with that either way.

Awesome factual UOA stuff in this thread though, I'd pay heed to that more than any other thing.
 

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If you feel a difference when using a thicker oil then you already have engine damage that the thicker oil is making up for. This will not last forever. The engine will continue to degrade no matter what oil you use.
 

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Ah, see well that's precisely the point.

I'm more concerned about what the wear rates look like past 100k miles. Thicker oil is better for high mileage engines, so I want to see how 0w20 will hold up in the long-run. I have no doubt that 0w20 is totally fine for the average conservative driver and is in fact beneficial for cold climates, but I just don't see why you need the quick flow on start up unless you are in -20c conditions consistently through the whole winter.



look how drastically the temperature range improves for hot weather when you use 5w30. this graph says that 5w20 is suitable for up to -10c weather...

for a climate like yours, 0w20 will simply not cut it. in Australia only 5w40 - 10w50 is specified. you're best off running a 5w40, and you will notice the engine running quieter and more smooth.

I am still completely lost as to why you are so against a thicker oil when 5w30 is used everywhere else in the world! up to 10w50 is allowed, and living in toronto I can safely back-up that 5w30 does not hurt anything during -20c starts, so why the hell would you use oil for siberian winter conditions living in a place like florida? I am dumbfounded at the stubborn approach you are taking toward this. how does 5w30 sound so bad to you if it is used in russia's frigid winters with zero issues? 5w30 has been proven in and out to be the overall better choice, plus it's been around for FAR longer then 0w20...

the only way we can come to some sort of agreement is if you try 5w30/40 and tell me if you notice a difference. if you genuinely notice no difference, then I guess i'm just crazy and all north americans should continue satisfying the CAFE requirements.




In my friends acura I didnt notice much of a difference switching from 0w20 to 5w30, but in my Mazda the difference was there without a doubt. standing by the car especially with the hood up all of that rattly valvetrain clatter was completely gone - only the sound of the injection ticking away and nothing else. it truly did sound more healthy and revving throughout the RPM's the engine felt more refined and smooth.

now that i've mentioned this, you could try 5w30 next oil change and just see if you notice any difference. given that the rest of the world uses minmum 5w30, I think it's fair to give both weights a try and determine for yourself what is best given your climate and driving style? I think this is what's important.
A couple of comments if I may:


  • Your oil chart is specific to a manufacturer's motor design criteria that includes internal clearances. It's not generic to all motors
  • I agree that the 20 weight oil was designed around CAFE requirements, however all modern 5W-20 or 0W-20 motor oil is at very least semi-synthetic and worlds away better than oil from years past
  • In the post that you quoted regarding fuel dilution it probable as some noted that the cause is a bad injector
  • I will not be able to try another oil as my dealer supplies free oil/filter changes using 0W-20 Quaker State Ultimate Durability Full Synthetic and Mazda OEM filters
  • You're obviously dug your heels into this position and are not willing to coincide any other opinion or science on the topic
 
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Looks like I'll be getting my oil checked sooner rather than later so I can post up the results here for everyone. I'm changing mine in less than 1k miles when I reach 110k.

I've run 0w20 since day 1, have zero (engine) mods or tunes, and have even run Shell gas every single fill up to see how it compares to Mobile/Gulf that I used in my V6.

I'm excited to see the results! :)

Edit: Oh and I live in New England, which is known to get kind of cold ;)
 

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I think I'm leaning heavily towards believing tickerguy over Get Inline.
 

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I ran the specified 0W20 in my skyactiv G mazda3 for 80k with no issues. Never had to add oil. MPG stayed linear but would fluctuate slightly based on different tires. I plan on running the same with my new mazda6 since it did so well and the motor proved so reliable. Oil weights and types are always debated rigorously in the rotary world since you are injecting it into the motor with the fuel. Rotella is the new popular choice since it can be had 0w40. People claim its the best thing since sliced bread and others claim the exact opposite. (Everything is factual on the internet right? lol) I would never run that in a skyactiv motor.

I do believe CAFE is the reason for 0w20 but since I had no issues with my prior engine, I would run it again. I would be far more worried with what actual oil is put into the car when you take it to a shop even though you specify it. The $12/hr oil tech is not going to care and service writers need to boost profits. I only do oil changes myself and I think that is just as important for why my prior skyactiv car did so well. I also do not think the skyactiv motors are exotic enough or being pushed hard enough to warrant thick oil. 0W20 is also the oil specified in my wife's Nissan Rogue which has a DI 4 cyl. Her first Rogue went 140k miles with no oil consumption.
 

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Discussion Starter · #18 ·
I ran the specified 0W20 in my skyactiv G mazda3 for 80k with no issues. Never had to add oil. MPG stayed linear but would fluctuate slightly based on different tires. I plan on running the same with my new mazda6 since it did so well and the motor proved so reliable. Oil weights and types are always debated rigorously in the rotary world since you are injecting it into the motor with the fuel. Rotella is the new popular choice since it can be had 0w40. People claim its the best thing since sliced bread and others claim the exact opposite. (Everything is factual on the internet right? lol) I would never run that in a skyactiv motor.

I do believe CAFE is the reason for 0w20 but since I had no issues with my prior engine, I would run it again. I would be far more worried with what actual oil is put into the car when you take it to a shop even though you specify it. The $12/hr oil tech is not going to care and service writers need to boost profits. I only do oil changes myself and I think that is just as important for why my prior skyactiv car did so well. I also do not think the skyactiv motors are exotic enough or being pushed hard enough to warrant thick oil. 0W20 is also the oil specified in my wife's Nissan Rogue which has a DI 4 cyl. Her first Rogue went 140k miles with no oil consumption.
I?ve used shell rotella 5w40 before. It flows extremely well on cold starts and elimated the cylinder head clatter I was getting in my BMW on cold starts completely, yet managed to lower oil temperatures noticeably and stayed nice and thick at full operating temp. It has too many diesel additives for my liking however, so I am thinking of switching to shell helix 5w40 for both my cars next oil change.
 

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Rotella T6 is an excellent diesel oil if it meets the specs for your car; my '03 TDI Jetta has run it since new, and has clocked roughly 240,000 miles thus far. Last time I had the valve cover off to do the timing belt (a few thousand miles back) the cam was in perfectly-serviceable condition. I have had no reason to pull anything on the bottom end.

That oil is, however, inappropriate for most gas engine vehicles and it's also inappropriate for PD-engined VWs (or common rail.) Using it in a PD engine (for example) is asking for a premature camshaft failure; it simply does not meet the requirements for that engine.
 

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My thoughts as I'm a little late for this

Thought I would share my experience switching from the Castrol 0w-20 garbage to Liqui-Moly 5w30. the engine felt much more refined. it ran 10x quieter and smoother then before, no more valvetrain clatter! just the smooth ticking sound of the DI. it revs smoother and overall feels much more solid then before. oil consumption has dropped from 1L every 9000KM to 1L every 15,000+KM. note that in Australia the following oils are approved:
0w20/30 (unless you start your car in-20C climate outside of your garage everyday, you should not be using this stuff because it's too thin)
5w40 (or 30) good for a variety of climates and driving conditions
10w30 Hot weather or aggressive driving
10w40
10w50 Track use
overall, highly recommend you do this if you live in a hot climate or drive the car hard.{/quote]
While I do not know the recommendations for your vehicle and climate, I do know that my 2003 2.3L recommends 5w20 year round. I personally think this is a little on the thin side and is a result of CAFE and other standards and manufacturers trying to compromise between durability and fuel economy. I will run 5/20 through the Wisconsin winter and be switching to 5/30 in spring.

Direct injection engines contaminate your supply of oil with fuel (fuel dilution) which breaks down your oil quicker then in other motors. this is why a good quality oil is important. from my experience, Motul and Shell rotella are the only two oils which are very tough and resistant during 5000+ mile intervals. the rotella is a diesel oil meaning it has detergents which are very useful for a DI motor (diesels are direct injected) for this reason, I recommend 5000 mile oil changes.
Oil itself does not break down; it is the additives within that have the issues, and getting fresh and proper amounts of additives is why we regularly change oils.
Newer ( and smaller) engines have brought in some new issues. Chrysler has had problems with drain holes being too small and being clogged with sludge. GM has recalibrated their oil life monitors due to concerns of performance and customer satisfaction. Ford has developed new tests for timing chain wear. And it is more than the Americans at work. The Europeans (ACEA) are working with oil manufactures to standardize the Ford test.
The GDI engines have an issue with deposits when run at low (engine) speed, creating hot spots within the engine leading to something known as Low Speed Pre Ignition (LSPI). What is happening is that the cylinders are over-pressurizing; normal cylinder pressure is around 650psi (44 bar), and when LSPI occurs they are near 1600psi (110 bar). Couple these high cylinder pressures with the low tension oil (piston) rings and there is your dilution problem. Wreckage is just waiting to happen.
As some of these deposits are actually on the intake valves which no longer get washed with the fuel/air charge, several manufacturers are stepping back and adding last generation port injection to clean them up.... like the new 3.5 Duratec/EcoBoost engine.

The international lube committee (ILSAC) is working on a new GF-6 oil standard which will most likely see a change in the detergents from calcium based to magnesium bases or some mixture. GM's "Dexos 1 Generation 2" licensed oils are made to meet the new LSPI tests.

Your recommendation for a diesel oil doesn't quite cut it; diesel engines generally have oil that is cooler than what you find in GDI passageways, especially when there is a turbo involved. So you will end up with even more deposits. Never mind that the additive package most likely will be completely wrong.
 
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