Mazda3 Forums banner

1 - 17 of 17 Posts

·
Registered
Joined
·
173 Posts
Discussion Starter · #1 ·
I came across an article that talked about the issue of using lighter/thinner weight oils and the fuel savings they may offer.

Interesting to note that the MAIN REASON on why 5w20 is recommended by Mazda is that it helps with CAFE standards. Compared with a 5w30 oil, the 5w20 oil, when its use is calculated in thousands of cars, with 100,000+ miles, it does help with their CAFE standards. Once again, it must be noted that this is when thousands of cars are calculated.

Now, when it comes to ONE car (yours), the numbers are negligible. For instance, in IDEAL conditions, if you take a 5w20 vs. 5w30 weight oil, driving over 50,000 miles, the 5w20 oil save you $147.00 in fuel costs. At 100,000 miles the 5w20 oil will save you $294.00 in fuel costs. Remember, these are ideal conditions and the best savings a 5w20 oil will give you is a potential 2% fuel economy improvement.

When you look at it based on ONE car (yours), the difference in fuel savings using 5w20 is really not that much. A dirty air filter will negate any fuel savings a 20 weight oil will give you. Low tire pressure will negate any fuel savings a 20 weight oil will give you. As will many other reasons, driving habits, etc.

I am switching to 5w30. After much research, reading many chemist articles about oil, the 30 weight oil is much better for high-temp situations, longevity and better protection over the 20 weight oil. The MAIN and ONLY reason on why 5w20 oil is recommended is because of CAFE standards. That is a fact. A 30 weight oil, overall, will give you better protection.

A 30 weight synthetic oil will have the following viscosity:
cSt @ 40º C 64.8
cSt @ 100º C 11.3
Viscosity Index, ASTM D 2270 169

A 20 weight synthetic oil will have the following viscosity:
cSt @ 40º C 48.3
cSt @ 100º C 8.8
Viscosity Index, ASTM D 2270 163

The difference is there. You can clearly see that the 20 weight oil has lower viscosity numbers. Add high RPM's, high heat, etc., the 20 weight oil will potentially give you more wear and less protection than a 30 weight oil would.
 

·
Registered
Joined
·
146 Posts
If Mazda engineered the car to be safe on 5w20, I'll keep my 2% efficiency increase please.

Why give it up if 5w20 isn't going to hurt it anyways?
 

·
Registered
Joined
·
41 Posts
[quote author=Funandfrugal link=topic=138417.msg2983123#msg2983123 date=1236611705]
5w20 in winter
5w30 in summer
[/quote]

agreed
 

·
Registered
Joined
·
173 Posts
Discussion Starter · #6 ·
[quote author=slyons89 link=topic=138417.msg2983043#msg2983043 date=1236608553]
If Mazda engineered the car to be safe on 5w20, I'll keep my 2% efficiency increase please.

Why give it up if 5w20 isn't going to hurt it anyways?
[/quote]

That is the $1Mil question. Car manufacturers DO NOT, I repeat DO NOT, care if your car doesn't last past 100K miles. They actually prefer it to NOT last over 100K miles as they want you to buy new cars, not keep them for 10+ years.

While 5w20 will be "OK" and most people will not have problems during their warranty periods, what about 150K or 200K miles?

It comes to down to which is better. 5w20 is good but 5w30 is better. When you add heat, high RPM's, the 5w30 will outperform 5w20 in viscosity & wear and tear.

So will 5w20 hurt anything during the 50K mile warranty period, yes, but not to the point that anything would fail. Will the 5w20 hurt the engine after 100K miles of use, I believe YES, and to the point of where it would now cause enough wear to cause a major failure.

Of course, driving habits, oil change maintenance, heat, location, etc., all play into this but if all was the same, the 5w30 will hold up better over the 5w20.

Remember, not EVERYTHING Mazda states is for the better. Look at the world, remember when they said Asbestos was the best thing in the world. They actually held Asbestos Conventions and it was looked as being the best thing in the world and used it to insulate pipes, made car parts, made home parts, etc. Unfortunately, they later discovered that it caused an incurable form of cancer of the lungs.

Doctors once prescribed cigarettes to patients. The medical profession looked at cigarettes as a GOOD THING and prescribed it to their patients. All the "experts" said that cigarettes were safe and good. Ooops!
 

·
Registered
Joined
·
253 Posts
Switching to 5w30 sure quieted my 2.3 down. I didn't notice any difference in fuel economy. Several other members have had similar results, Im sure they will stop in.

The only reason 5w-20 was developed was for CAFE standards. Its simple, its a thinner oil. Which equals less protection and a (neglible) increase in fuel economy. Have you noticed lately that many OEMs are all of sudden recommending 5w20 when the same engine has called for 5w-30 (or even 10w-30) in the past? Hmmmmm
 

·
Registered
Joined
·
1,129 Posts
[quote author=stranger706 link=topic=138417.msg2984136#msg2984136 date=1236638997]
Have you noticed lately that many OEMs are all of sudden recommending 5w20 when the same engine has called for 5w-30 (or even 10w-30) in the past? Hmmmmm
[/quote]

Yes and not only that but I had cars from the mid 1980s where the owners manual specified up to 20w-50 oil and gave temperature ranges for the various weights to be used. I believe 10w-30 was the overall recommendation as it covered most of the temp ranges where as say 20w-50 was just for warmer climates or warmer times of the year.
 

·
Registered
Joined
·
146 Posts
I'm sorry but it seems kind of like overkill.

By the way, a 2% fuel economy increase is not negligible, IMO, especially considering that new technologies like stop-start engines barely increase fuel economy by this much. Also remember that this fuel economy payoff does not tax your vehicle's performance (acceleration).

For example, take a look at this new regenerative exhaust system being engineered by BMW with NASA:
http://www.autoblog.com/2009/03/10/bmw-working-with-nasa-on-regenerative-exhaust-system/
This highly advanced technology may only increase fuel economy by 5%. Is this still too marginal to bother including it? It's all the little innovations in cars that will make them efficient and viable in the future. Wait til gas is $5 per gallon, every % will matter...

And maybe CAFE has the right idea anyways. 2% more fuel economy from every car is millions of gallons saved, and tons less Co2 being poured into the atmosphere.

Besides that, I mean, I love my car but I'm not exactly planning on keeping her until 200k miles rolls on the clock. Probably before 150k, I'll be looking for something new. So for me, and perhaps for others on this board, the engine wear is what is negligible.
 

·
Registered
Joined
·
253 Posts
Some good points there. Don't get me worng, Im all for better fuel mileage. I just meant for me it was a negligible difference. My mpg didn't change at all with the 30 weight. I know there are other factors involved but the biggest thing I noticed right away was the decrease in engine noise. Although Im still not sure if this is due to the heavier weight, or the different brands.

Its easy to get excited about better corporate fuel economy. But then I drive to work, and watch how most people drive, and all those 2% and 5% increases in fuel economy go out the window. Most people drive TERRIBLE (in relation to fuel mileage). Its a freakin nascar race everywhere you go. And thats the biggest factor right there, people's driving style. So how are all these advances in fuel mileage going to be effective if people don't have the right mindset about it?
 

·
Registered
Joined
·
146 Posts
Touche'

While i've been arguing on the side of fuel economy, I'm no hypermiler, and i love hearing the engine rev, haha. Achieving better fuel economy even with crappy driving style, now that will be a feat. I think Ford has the right idea with their hybrid systems, in how dash display actually guides your economy and gives you graphical feedback to help you drive smoothly and more efficiently, instead of just letting everything go on in the background. It trains you!

If the heavier oil makes things run more smoothly in my mazda, i'm curious to see if i notice the difference. Maybe when I take my long road trip in the middle of the summer this year I'll beef up protection with the 5w30 and check it out.
 

·
Registered
Joined
·
173 Posts
Discussion Starter · #12 ·
[quote author=slyons89 link=topic=138417.msg2985241#msg2985241 date=1236694756]
By the way, a 2% fuel economy increase is not negligible, IMO, especially considering that new technologies like stop-start engines barely increase fuel economy by this much. Also remember that this fuel economy payoff does not tax your vehicle's performance (acceleration).

Besides that, I mean, I love my car but I'm not exactly planning on keeping her until 200k miles rolls on the clock. Probably before 150k, I'll be looking for something new. So for me, and perhaps for others on this board, the engine wear is what is negligible.
[/quote]

There are A LOT of factors at play here. I live in Arizona and the heat (110F) is really bad in the summer. The 5w20 weight oil would damage my engine faster than it would with someone driving in a different climate. When it's 110F outside, I'm climbing a 5% grade with the A/C on, the temps and load on that oil are getting extreme. A 30 weight oil, especially synthetic, will make a big difference.

People drive with low tire pressures. This can reduce fuel economy by 5%+. People drive with dirty air filters, this can reduce fuel economy by 5%. So now you have a combined loss of 10%. Add hard acceleration and other driving factors and that 2% gain has all been gone long, long ago.

Here is another thing to look at. With the 20 weight oil, the engine only lasted 100K, instead of 200K, and now you have how much more resources and pollution in order to make a NEW car and/or rebuild a motor. Remember, it is better for the environment to keep an old car on the road, than tool, test, and build a new car. That has already been proven time and time again.

Toyota just announced that it is cutting its supply. It is building LESS cars, and that is actually BETTER for the environment.

Remember, Mazda along with other car manufacturers will play the system in order to save money and get by with gov't standards. The 20weight oil is IMHO one of those games. A better designed engine that gets 35MPG would be better than an engine that gets 29MPG with 20weight oil and maybe would get 28.5MPG with 30 weight oil.
 

·
Registered
Joined
·
358 Posts
[quote author=Lbear link=topic=138417.msg2982849#msg2982849 date=1236579466]
I came across an article that talked about the issue of using lighter/thinner weight oils and the fuel savings they may offer.

Interesting to note that the MAIN REASON on why 5w20 is recommended by Mazda is that it helps with CAFE standards. Compared with a 5w30 oil, the 5w20 oil, when its use is calculated in thousands of cars, with 100,000+ miles, it does help with their CAFE standards. Once again, it must be noted that this is when thousands of cars are calculated.

Now, when it comes to ONE car (yours), the numbers are negligible. For instance, in IDEAL conditions, if you take a 5w20 vs. 5w30 weight oil, driving over 50,000 miles, the 5w20 oil save you $147.00 in fuel costs. At 100,000 miles the 5w20 oil will save you $294.00 in fuel costs. Remember, these are ideal conditions and the best savings a 5w20 oil will give you is a potential 2% fuel economy improvement.

When you look at it based on ONE car (yours), the difference in fuel savings using 5w20 is really not that much. A dirty air filter will negate any fuel savings a 20 weight oil will give you. Low tire pressure will negate any fuel savings a 20 weight oil will give you. As will many other reasons, driving habits, etc.

I am switching to 5w30. After much research, reading many chemist articles about oil, the 30 weight oil is much better for high-temp situations, longevity and better protection over the 20 weight oil. The MAIN and ONLY reason on why 5w20 oil is recommended is because of CAFE standards. That is a fact. A 30 weight oil, overall, will give you better protection.

A 30 weight synthetic oil will have the following viscosity:
cSt @ 40º C 64.8
cSt @ 100º C 11.3
Viscosity Index, ASTM D 2270 169

A 20 weight synthetic oil will have the following viscosity:
cSt @ 40º C 48.3
cSt @ 100º C 8.8
Viscosity Index, ASTM D 2270 163

The difference is there. You can clearly see that the 20 weight oil has lower viscosity numbers. Add high RPM's, high heat, etc., the 20 weight oil will potentially give you more wear and less protection than a 30 weight oil would.
[/quote]

[quote author=Funandfrugal on March 09, 2009, 11:15:05 AM]

5w20 in winter
5w30 in summer

[/quote]

Reviving an ancient thread.

I use 5w30 for two-thirds of the year, just this past Saturday changed over to thinner 5w20 for winter (Valvoline semi-synth). Good timing, cold moved in today.
 

·
Registered
Joined
·
1,900 Posts
Yeah I do the same, 20w during the winter cause I' am anal and I'll set there for 5 minutes warming my car up watching for the oil pressure to drop from 90psi (cold weather thick viscocity) to @40-35psi and oil temp rise to atleast 110, running 20w lessens this time, and summer I run 35w (custom mix 30w and 40w equal parts).
 

·
Registered
Joined
·
358 Posts
tabasco, are you saying you use straight 20w? And a mix of straight 30w/40w in summer? I didn't think using non multigrade oil made sense anymore.
 

·
Registered
Joined
·
1,900 Posts
lol ahh 5/20w and a mix of 5/30w&5/40w same brands, same oil different viscocity-no harm no foul
 
1 - 17 of 17 Posts
Top