Synthetic Oils-There is a difference!

[outbackfan]

I have an '00 Outback Wgn 5speed. This car just gets better and more enjoyable every day. 68k miles, and runs BETTER than day 1.

 

Recently replaced engine oil w/Mobil1 5w30, and tranny-transaxle/rear differentials w/Mobil1 75-90.

 

After 500 miles, hwy mileage has gone from 25->27mpg, and combined has gone from 23->25mpg. Subjectively, the car FEELS smoother and quicker. Has anyone else experienced this?

[Smpol19]

Yup at the exact same millage (68k) i changed to the same oils you did on my 01 Impreza OBS 2.2l, I'm almost to 80,000 miles now and I noticed the same change in gas millage you did about 2 more miles on avrage.

[Setright]

Yes sirree!

 

 

But don't tell the mineral-oil-only crowd, they'll think we're nuts!! Let them waste fuel in peace :-)

[friendly_jacek]

Sure you get increase in MPG with mobile 1 5W30. It is not a magic "slippery synthetic" urban legend effect. The mobil 1 5w30 oil has one of the lowest viscosities for 5W30 oil (close to 9 cSt at 100C IIRC). Most dino oils in 5W30 start at 12-13 cSt (whoping 30-40% higher than mobil 1) to allow for shearing viscosity down cuz dino relies on unstable VI improvers additives to increase viscosity at high temp.

You have to understand though that the lower viscosity goes, the HTHS goes lower (index of oil protection at high stress/high temp, or conditions at the piston rings).

Unfortunately, every oil has to a reach a compromise between better fuel economy and better protection at high temp. Mobil went the MPG route. Performance oils from europe (EACE B3 certified) and heavy duty engine oils (the ones with both API SL/CH-4 or newer) go the high HTHS (and lower MPG) route.

 

The comment:

"But don't tell the mineral-oil-only crowd, they'll think we're nuts!! Let them waste fuel in peace :-)"

is very immature and poorly informed. If you want, you can use dino 5W20 (8-9 cSt at 100C) oil and you will observe a similar increase in MPG (reason that Ford and Honda recently switched to 5W20 oils for almost entire fleet).

 

Use the oil that suits your driving styles.

I do some towing in hot summers, so I will never touch an oil will HTHS less than 3.6 (or below the EACE B3 standard) during summer season. Using heavy duty synthetic 5W40 oil (14.6 cSt @100C; HTHS of 4.0), synth ATF (mobil 1 ATF) and synthetic diff oil (redline 75W90) I do not observe an increase in MPG compared to 5W30 or 10W30 dino oil (used for short intervals in winter). YMMV.

[Setright]

I fail to see what is so immature about humour. The oil debate will never end, and I was only trying to bring a smile to people's faces.

 

Besides, I run Mobil 1 5W-50 and that improves mileage over the dealer filled mineral 10w-40. You can't explain that away with viscosity indexes. Oil has internal friction, and I would argue that Mobil 1 has less than most other oils.

[Setright]

Oh, and the synthetic oil will not veer from it's viscosity rating under shear load in bearings - mineral oil with VI's will.

[Ranger83]

If manufacturers could get a nearly 10% increase in fuel economy by switching to synthetic oil, conventional oil would have gone the way of the dinos who gave their lives for it.....

 

I have a '97 OBW and usually get combined mpg of 25.5. But I've gotten individual tanks as high as 28.1 and as low as 20.0 in all city driving.

 

So the change you've described is well within the "normal" range. If you'd recorded your mileage for the last 5,000 miles, and the next 5,000 miles, that would be more meaningful. Do you have the accurate mpg #'s for the last 5,000?

 

 

 

But changing to synthetic is very unlikely to have made your mileage worse.

[Setright]

I must disagree. Almost any manufacturer, of almost any product will always try to force the cost of production down. Accountants have a very big role in product design.

 

Synth IS better, and that's why Porsche uses Mobil 1 as factory-fill. Same goes for AMG tuned Mercedes. The price of the car itself can easily cover up the addded expense of oil.

 

However, if you are seeking to produce millions of cars and selling them in a competitive price range, then the oil price is a deciding factor.

 

Please don't try and tell me that "economies of scale" would reduce the cost of synthetic if all car companies switched. One of them has to make the first step, and car companies are far too conservative for that.

[blitz]

Synth IS better

 

Define "synthetic". Now THERE'S humor!

[outbackfan]

Interesting discussion. Some thoughts-

 

(1) Viscosity Index. A comment was made that Mobil 1 5W30 is less viscous than other 5W-30's, so mileage should incrase. Fair enough. But this does not translate into inferior friction protection, as the Mobil 1 and independent testers will note - synth engines always have less wear when they're torn down.

 

(2) Mileage improvement- observation after 500 miles was done over two tankfulls of gas, one on a fwy road trip and one on typical combined driving. My mileage prior had been rock steady at 25/23 (fwy/combined)-I always calculate at fillup. So I'm confident that this is a true reading and not a statistical aberration.

 

(3) I must agree that auto mfgrs ('cept BMW) are so price competetive that they won't include synth as factory fill-no advantage in securing the purchase from the average consumer who couldn't care about the oil, and chooses his new car based on the macho ads shown on tv.

 

Cheers!

[Ranger83]

I must disagree. Almost any manufacturer, of almost any product will always try to force the cost of production down. Accountants have a very big role in product design.

 

Synth IS better, and that's why Porsche uses Mobil 1 as factory-fill. Same goes for AMG tuned Mercedes. The price of the car itself can easily cover up the addded expense of oil.

 

However, if you are seeking to produce millions of cars and selling them in a competitive price range, then the oil price is a deciding factor.

 

Please don't try and tell me that "economies of scale" would reduce the cost of synthetic if all car companies switched. One of them has to make the first step, and car companies are far too conservative for that.

Right, two cars with very highly tuned engines and no concern over fuel economy specify synthetics as stock. So do Corvettes and M1 tanks. The question at hand is if it yields a nearly 10% improvement in mileage, or really if it improves mileage at all.

 

Accountants seldom have any role in automotive design and development. Or perhaps I can be more precise by saying that in my time in the R&D group of parts supplier to Chrysler, GM, Ford, and VW I never met an accountant. All engineers are concerned with value engineering, and all systems have cost targets - and tooling cost targets - to maintain.

 

If the original poster has recorded his precise mileage for the last 5,000 miles - and that's only one or two oil changes - and then records it for another 5,000 with the synthetic and still nets a nearly 10% increase in fuel mileage, then it will be a more persuasive argument.

[bgambino]

interestingly, my wife's new Honda CRV calls for 5/20....1st time i've heard of it being used.....but I am from the old school...not interested in syn. oils....will use 5/30 every 3000....the car will surely run 250K (that is, if I were driving it...her?...who knows)

 

PS...she was paying $50 for an oil change at the dealer....I said...WHAT THE HELL FOR!!!!!!!!??????

She mentioned the recent fire problems bla blah blah....I called the service dept and said ...whats up with the fire hazard?....it was all about letting oil drain on a hot exh manifold...and he said sometimes people have left to old gasket in place....

Holy CRAP......I told her...that's the last time you're going to those crooks

[Setright]

Blitz !

 

 

Ranger, I cite the Porsche and AMG choice to highlight the protection of Mobil 1. Of course, you cannot overlook their desire to free up as much power to the wheels, instead of losing it in the oil.

[blitz]

Blitz !

 

Har! Har! I 'spose the second part of the question is: define "better".

 

The group IV & V (PAO & POE) types excel at both long oil change interval and low-temp flow properties, that fact can't be denied. I do think however that the performance gap between synth & conventional has narrowed appreciably in the last 20 years.

 

Having lurked on BITOG for some time, I've noticed a tendency for the new semi-synth oils (various blends of group II, II+, III) to show some of the lowest wear rates for some unexplained reason. Also thankfully, the price on the semi-synths are dropping, now that more OEM's are specing them as required fill (Ford, Honda, etc.)

 

As far as the power aspect goes I will add this: a friend of mine who works at Maclaren in Livonia, Michigan, assembling and dynoing lease engines for racing use, told me that they've been filling exclusively with Mobil 1 0W-40.

[simbey1982]

any objective proof....less rants?

[Setright]

Erm...well..the best objective proof I can muster is that Porsche and AMG choose Mobil 1.

 

BMW selects Castrol's fully synth.

 

 

At least that means these oils aren't crap.

[Ranger83]

 

Ranger, I cite the Porsche and AMG choice to highlight the protection of Mobil 1. Of course, you cannot overlook their desire to free up as much power to the wheels, instead of losing it in the oil.

Sir, I am only questioning the original poster's claim that his gas mileage has improved nearly 10%.

 

I raced cars for several years and always did precise before-and-after performance tests on any changes made. You always subjectively believe that a change you've made and spent money on improves performance. Scientific Method often indicates otherwise.

 

But if you believe him, with gasoline at anywhere from $2-4 per gallon, this mileage improvement is well worth the expense and everyone should run right out and make the change.

 

As I already get better mileage than that on average with an automatic 97 OBW with 150K miles on it, I'm not interested.

 

I have my engine oil analyzed by www.natrib.com, an oil analysis firm every 50K miles. There's no reason for me to change to a synthetic. Not even the synthetic manufacturers claim an improvement like this - they post testimonials, instead.

 

Lets hear back in 5,000 miles about the averages before and after. I'm skeptical about this claimed improvement for a couple of reasons.

 

First, because he has mileage for city and highway - is he driving an entire tank in the city, and an entire tank on the highway, or is he mingling the two numbers as estimates?

 

Second, I can calculate my mileage to 10ths of a gallon, so round numbers make me sceptical - rounding up or down could account for a third of the claimed improvement.

 

Third, as mentioned previously, the mileage given as the baseline is at the low range for this vehicle, so any driving style change would likely move the average up. What mileage are others getting with manual shift 00-03 vehicles in mixed driving?

 

But as they say, "No one would be happier to be proven wrong."

[Setright]

Well, my experience with many cars, over many years has been an improvement of 4-5% when they were switched to Mobil 1. I am not talking about brand new cars that were only just running in.

[Chip]

I'm not a "Math Whiz" so I'll let someone else do the figuring but assuming mpg improved by, let's say 7%, would it cover the increased cost of the synthetic oil ?...(assuming that the oil changes were still done around 5K).

[Setright]

Chip, that would be part of the idea. Extend drain intervals. You could do like me and replace oil and filter between 6 and 7 k miles.

 

Or, as I am starting to consider, replace the filter at 5k, top up the oil, and not actually drain until you reach 10k. That would easily match the price of mineral.

[Philbiker]

I thought extended drain intervals with synthetic was a myth.

[frag]

I thought extended drain intervals with synthetic was a myth.

It is. The limit here is not the oil itself breaking down, it's the oil's ability to hold contaminants in suspension. That part is no better with synth than with standard oil.

I use synth for better cold starting and for it's better lubricating qualities. I try to keep change intervals near what they are supposed to be, 5000km.

[friendly_jacek]

It is. The limit here is not the oil itself breaking down, it's the oil's ability to hold contaminants in suspension. That part is no better with synth than with standard oil.

I use synth for better cold starting and for it's better lubricating qualities. I try to keep change intervals near what they are supposed to be, 5000km.

This is a good point. The standard oil filter does not protect against the most common oil contaminants: water condensation and unburned fuel. So, if one drives short distances in cold weather or has a rich burning engine, exended intervals on synthetic make no sense.

On the other hand, with lots of highway driving, and properly tuned engine, 10-15,000 miles is not a problem with quality synthetic oil.

 

Synthetic oils shine in cold temps or heavy duty or turbo applications.

Someone above mentioned mobil 1 0W40, it is it a good oil (HTHS of 3.5 IRRC). Mobil's 5W40 is even better for heavy duty (HTHS 4.1).

I am not bashing synthetic oils, I use one myself. I just want people to be aware that the MPG savings with mobil 1 5w30 and 10W30 is due to very thin nature of these oils (low 30 weight).

[Philbiker]

On the other hand, with lots of highway driving, and properly tuned engine, 10-15,000 miles is not a problem with quality synthetic oil.

I'd be willing to bet that this statement would be true even if it was not qualified. That is, 10-15K miles wouldn't be a problem on that car with quality conventional oil either.

[friendly_jacek]

Maybe, but only with close monitoring with oil analysis. Group 1 oils would likely oxidase, thicken, and possibly sludge at these intervals. However, these days, with API SM/ILSAC GF-4 certification, "conventional" oils are group 2, group 2+, or mixture of group 1/3, so the performance is much closer to the synthetic levels.