[Padawan]

At least older US-spec smarts were 10:1 compression ratio, while the N/A smarts for the rest of the world were 11.4:1.

Some of the earlier documentation stated that they were 10.0:1, but I have yet to see anyone present actual evidence (different part numbers across the model years for pistons, rods, etc.) to indicate that this discrepancy was anything other than an erroneous figure in the manual.

Even if the earlier US-spec cars were in fact delivered with a lower compression ratio, the change would not necessitate a different oil specification from that of the ROW cars running a higher compression ratio. And as the higher compression ratio began being listed in the literature at least as early as 2011, it would certainly offer ample time to "update" the oil chart accordingly to ROW-specs if that were indeed the reason for the original modification to the 30 weight values.

 

[Padawan]

Now I am getting even more confused (between jwights chart & evolutions chart)

The chart on Evilution's site is the one smart has provided outside of the US for a number of years.

If you have difficulty accepting that Mitsubishi somehow re-worked the 3B21 exclusively for the US market in such a way as to require different lubrication than the engine it provides to smart for the rest of the world, then the Evilution chart is fine.

You might also be interested in learning that it had previously been determined that Mitsubishi delivers the engines to smart filled with a non-synthetic oil (most likely 5W-30).

 

[jwight]

Now I am getting even more confused (between jwights chart & evilutions chart) LoL! Because if I can use a 5w-30 or even a 10w-40 then I can get those for a much lower price then do the change @ every 5,000 and be fine with that...BUT now what about semi-synthetics? I ask this simply for the reason that my local shop does a semi-synthetic 5w-30 oil change for $9.99! Now, I am not trying to be "cheap" (as I don't mind paying for confidence,safety and security) but since I will be doing a minimum of 500+ miles a week my oil change schedule will be a lot more often than most and being frugal/economical in these times is not the same as being "cheap".

If you're operating the engine under "severe" conditions then more frequent oil changes are called for by the owners manual. No matter, Mercedes specifies synthetic oil for the Mitsu engine. No doubt it will run fine with dyno oil, but for how long? :wink:

 

[deepblueQ]

Don't worry, I'll let everyone know if the smart blows up....

You're in Ohio, so if you do go above 86*F it probably won't be by more than the margins they spec'ed into the shift points. Now, if you were to go for a 4th gear highway run on a 95*F day, then get back into town and back to auto mode, that would probably be very bad...

I use 0W30 myself, I'm just careful with the revs on hotter days.

Now I am getting even more confused (between jwights chart & evilutions chart) LoL! Because if I can use a 5w-30 or even a 10w-40 then I can get those for a much lower price then do the change @ every 5,000 and be fine with that...BUT now what about semi-synthetics? I ask this simply for the reason that my local shop does a semi-synthetic 5w-30 oil change for $9.99! Now, I am not trying to be "cheap" (as I don't mind paying for confidence,safety and security) but since I will be doing a minimum of 500+ miles a week my oil change schedule will be a lot more often than most and being frugal/economical in these times is not the same as being "cheap".

10W40 will be just as good as 0W40 as far as engine wear goes (at least in your climate), but if you use the 10W then your fuel economy will really suffer until the engine gets warmed up. Much more of an issue if you make lots of short trips, as opposed to fewer longer ones.

I'd still stay away from 5W30, but it's your car.

I'd also stay away from semi-synth, but I'm not nearly as opinionated on that as viscosity. Chances are you'd never know the difference for using it... it'd just be more wear of the gradual sort.

Some of the earlier documentation stated that they were 10.0:1, but I have yet to see anyone present actual evidence (different part numbers across the model years for pistons, rods, etc.) to indicate that this discrepancy was anything other than an erroneous figure in the manual.

Even if the earlier US-spec cars were in fact delivered with a lower compression ratio, the change would not necessitate a different oil specification from that of the ROW cars running a higher compression ratio. And as the higher compression ratio began being listed in the literature at least as early as 2011, it would certainly offer ample time to "update" the oil chart accordingly to ROW-specs if that were indeed the reason for the original modification to the 30 weight values.

Larry's screaming cow got to 23 lbs of boost on stock internals before it blew up, and when it did it wasn't because of knock, burned valves, preignition, or anything like that... it was just that a compression ring wasn't sized right for those temperatures. As far as I've heard, there aren't many engines out there with normal 9.x:1 compression ratios that can take that kind of boost on stock internals. An 11.4:1 engine that could handle abuse like that would be quite a feat indeed.

To put things in perspective: 22 lbs = 1.5 bar, so 2.5 atm absolute... 2.5 * 11.4 = 28.5... 28.5 / 9.5 = 3 atm absolute, so 22 lbs @ 11.4:1 is roughly equivalent to 30 lbs @ 9.5:1, except it's even crazier than that since a bigger percentage can be intercooled on the lower compression engine.

Do you know of any originally N/A engines that can take 35 psi boost on stock internals?

The chart on Evilution's site is the one smart has provided outside of the US for a number of years.

If you have difficulty accepting that Mitsubishi somehow re-worked the 3B21 exclusively for the US market in such a way as to require different lubrication than the engine it provides to smart for the rest of the world, then the Evilution chart is fine.

You might also be interested in learning that it had previously been determined that Mitsubishi delivers the engines to smart filled with a non-synthetic oil (most likely 5W-30).

Mitsu most likely doesn't do the ECU/TCU programming. The ECU is Bosch, the TCU is most likely Getrag. There's a lot of room for difference there... did that source mention if MB changed the oil before sending them out?

 

[Oner001]

10W40 will be just as good as 0W40 as far as engine wear goes (at least in your climate), but if you use the 10W then your fuel economy will really suffer until the engine gets warmed up. Much more of an issue if you make lots of short trips, as opposed to fewer longer ones.

I'd still stay away from 5W30, but it's your car.

I'd also stay away from semi-synth, but I'm not nearly as opinionated on that as viscosity. Chances are you'd never know the difference for using it... it'd just be more wear of the gradual sort.

The fuel economy when "cold" per se shouldn't be that much of an issue since it is always hot down here, thus between the intake air temp being hotter and the ambeint temp of the block being warmer (because the car sits in the sun all the time) I think 10w-40 would be the greatest compromise and effectiveness in my sitaution as it will get to operating temperature quickly. So I believe I can get a less expensive (but still quality synthetic oil) and do them myself easily/quickly at a 5k interval for my peace of mind!

I have to say Thank You to all who have offered their help, comments, insight and info about this. It is GREATLY appreciated!

 

[Pee-wee Germa]

How about 5W40 instead of 10W40?

 

[Oner001]

How about 5W40 instead of 10W40?

That's also a possibility, just have to wait 'till I get home to do some price searching/comparisons.

 

[deepblueQ]

The fuel economy when "cold" per se shouldn't be that much of an issue since it is always hot down here, thus between the intake air temp being hotter and the ambeint temp of the block being warmer (because the car sits in the sun all the time) I think 10w-40 would be the greatest compromise and effectiveness in my sitaution as it will get to operating temperature quickly. So I believe I can get a less expensive (but still quality synthetic oil) and do them myself easily/quickly at a 5k interval for my peace of mind!

10W40 will still be around 2/3rds thicker when you first start it up than 0W40, even in your climate. 5W40 would be much better.

 

[a2jack]

I've got some Mobile 1 ,0W-20 around. Can I run this safely in moderate weather at freeway speeds ? A2Jack

 

[Oner001]

Looks like I will be almost definitely using this ~ Shell Rotella Full Syn 5w-40 @ $22 a Gal...now for oil filter options :wink:

 

[Rustedwrench]

Either the 0W-40 or the 5W-30 should be fine, IF the 5W-30 is approved for use in European engines. The European approved oils have a higher dynamic viscosity at operating temperature. A European 5W-30 can be thicker at operating temperature than a generic 5W-40. Avoid 5W-20, 10W-40 oils.

Use a quality filter. The cheap ones can shed filter material from the media and clog oil passages.

Oil and filters are relatively inexpensive in the grand scheme of things compared to internal engine repairs.

 

[deepblueQ]

I've got some Mobile 1 ,0W-20 around. Can I run this safely in moderate weather at freeway speeds ? A2Jack

Moderate weather means W30 would be acceptable by the MB spec, so let's use that as the baseline.

W30 = 10-13 cSt when warmed up, W20 = 6-9 cSt when warmed up. 7 / 12 = 0.58, so when using 0W20 you should only assume you've got 60% or so of the BOC you would with xW30.

Use manual mode and keep it revved 60% higher than you normally would when lugging is the issue (I'd say use 5th strictly for maintaining highway speeds, and grab 4th for even small hills or headwinds). Also treat redline as sqrt(0.6) * 6500 = about 5000 RPM. Don't use A/C at idle... that's 50 kPa MAP @ 1050 RPM, which is borderline even on the proper oil.

 

[Brabus007]

And what do you tell owners that have ignored all this, and have over 100,000 miles on their engines, and still going strong...? The tranny shifts down when it determines the drive-train & engine are under excessive load (I find my cars computer has this load situation figured out vary well)...

 

[1983JZR3W]

Today, I bought four quarts of Mobil 1 0W-40 and a Mobil I M1-108 oil filter at a local Pep Boys. $9.39 per quart and $13.59 for the filter. I will change it in the morning. My car just turned 2900 miles this morning, but I change by the one year rule.

 

[deepblueQ]

And what do you tell owners that have ignored all this, and have over 100,000 miles on their engines, and still going strong...? The tranny shifts down when it determines the drive-train & engine are under excessive load (I find my cars computer has this load situation figured out vary well)...

The TCU calculates what load is acceptable according to one particular oil viscosity. It doesn't have oil temperature or pressure sensors (besides the pressure switch), so it doesn't have any clue what the actual viscosity is at the moment. If you put in 0W20 and go for a 4th gear highway run in Florida, then the viscosity is going to end up far lower than the TCU is expecting, no question about it.

I realize there are plenty of people who have ignored this and haven't blown their engines. I expect that they are not in exceptionally hot climates, don't drive it very hard, keep the revs a bit higher, or some combination of the above. Even so, I would expect that their bearings are worn a fair bit more than engines run within spec. MB has to design for extreme situations... when you put in thinner oil, you're just taking away much of that room for error that they built in.

 

[Rustedwrench]

And what do you tell owners that have ignored all this, and have over 100,000 miles on their engines, and still going strong...? The tranny shifts down when it determines the drive-train & engine are under excessive load (I find my cars computer has this load situation figured out vary well)...

I do not know to whom you are addressing your question, but I tell people unless I state otherwise, I am offering my opinion. Nothing more. No guarantee, one way or the other. It is your car and you do as you wish. You may do everything wrong and come out right or do everything right and come out wrong.

It may be a digital age but it is still a analog world where things are not black and white but exist in shades of gray.

 

[Brabus007]

Today, I bought four quarts of Mobil 1 0W-40 and a Mobil I M1-108 oil filter at a local Pep Boys. $9.39 per quart and $13.59 for the filter. I will change it in the morning. My car just turned 2900 miles this morning, but I change by the one year rule.

You followed the Smart manual recommendations precisely... I would expect good long term results... You get my vote...<)

 

[rfernatt]

I'd stick with the 0W-40.

You can also pick up Mobil1 0W-40 and the M1-108 filter at Amazon. There is usually a $15 rebate if you buy the oil and a filter. You can buy 6 quarts of 0W-40 for $56 and (2) M1-108 filters for $22 and qualify for the $15 rebate. That also includes free shipping and no sales taxes.

 

[Pee-wee Germa]

Quote from another forum just to keep this interesting:

a 0wXX oil is really a 5wXX that has a lower pour point than 5wXX. 0wXX is able to pour at temps below -45C.

to achieve such a low pour point, Group IV and V synthetic basestocks had to be used...meaning that a 0w oil was indeed a true synthetic and not synthesized from crude oil like a Group III. Recent advancements have had Group III oils with lower pour points than -45C.

a 0wXX oil can be thicker in viscosity at 40C and 100C when compared to a 5wXX oil

Example:

Mobil 1 0W-40
SAE Grade 0W-40
Viscosity, ASTM D 445
cSt @ 40ºC 80
cSt @ 100ºC 14.3
Viscosity Index, ASTM D 2270 187
Sulfated Ash, wt%, ASTM D 874 1.2
HTHS Viscosity, mPa-s @ 150ºC, ASTM D 4683 3.6
Pour Point, ºC, ASTM D 97 -54
Flash Point, ºC, ASTM D 92 236
Density @ 15ºC kg/l, ASTM D 4052 0.855

and, compared to Mobil1's 5w30

Mobil 1 5W-30
SAE Grade 5W-30
Viscosity, ASTM D 445
cSt @ 40ºC 64.8
cSt @ 100ºC 11.3
Viscosity Index, ASTM D 2270 169
Sulfated Ash, wt%, ASTM D 874 1.0
HTHS Viscosity, mPa-s @ 150ºC, ASTM D 4683 3.09
Pour Point, ºC, ASTM D 97 -45
Flash Point, ºC, ASTM D 92 230
Density @ 15ºC kg/l, ASTM D 4052 0.80

the supposedly thinner 0w40 has a higher viscosity at 40C than the 5w30. notice that the pour point of 0w40 is -54C and 5w30 is -45C


Comparing the Mobil1 0w40 to Motul X-Cess 5w40, the 5w40 specs are:

Viscosity, ASTM D 445
cSt @ 40ºC 92
cSt @ 100ºC 14.6
Viscosity Index, ASTM D 2270 165
Pour Point, ºC, ASTM D 97 -33
Flash Point, ºC, ASTM D 92 230
Density @ 15ºC kg/l, ASTM D 4052 0.853

The Motul 5w40 has a higher viscosity at 40C but a lower pour point (-33C) when compared to Mobil1 0w40. At 100C, the 0w40 and 5w40 have very close viscosity ratings (difference of 0.3).

 

[dhirtle]

Either the 0W-40 or the 5W-30 should be fine, IF the 5W-30 is approved for use in European engines. The European approved oils have a higher dynamic viscosity at operating temperature. A European 5W-30 can be thicker at operating temperature than a generic 5W-40. Avoid 5W-20, 10W-40 oils.

Use a quality filter. The cheap ones can shed filter material from the media and clog oil passages.

Oil and filters are relatively inexpensive in the grand scheme of things compared to internal engine repairs.

Is that a general recomendation of strictly related to use w/ a smart? I ask because I have a vehicle that the manufacturer recommends 5-20W. So far it's been fine but mileage is getting up there.