Summer/Winter Gasoline

[Grumpy Bear]

I ran a Esso Model IV Fluid cat cracker for Chevron USA making gasoline, light diesel and avgas components. Even wrote the some of the operating manuals for the equipment and processes. I didn’t pull this from a Google search. No need to. I was part of the five man team that ran the unit. Also have a few years in research pulling gasoline from shale oils for...Chevron Research. Regardless of the crude stream the end product is the same.

 

Reid Vapor Pressure is adjusted four times a year, not twice. A sample of gasoline is placed in a container and brought to the 32 F spec with a 0 to 15 psig gauge installed. Once stable it is confined (valve closed) and placed in a water bath to come to equilibrium temperature of 100 F and the pressure recorded. C3H8 and C4H10, propane and butane respectively are added to adjust the vapor pressure to the Federal regional and seasonal VOC (volatile organic compounds) specifications. Plus minus 1 psig. That is the total difference between “summer” and “winter” gasoline. A few percent of dissolved LPG.

 

Winter gasoline does not give poor mileage because it is some witches brew that has some lower or significantly different energy content. Winter and summer blends have the EXACT same D-86 distillation initial and 90%. The test that verifies the chemical makeup of the fuel. This isn't all that new and it isn't all EPA. In the day of carburetors fuel systems would vapor lock in the summer or your car would fail to start in the winter due to little vapor in the cylinder without these adjustments. It was the EPA that made it visible to the public and forced structured refinement of the test for VOC emissions at the tank. Neat little marketing tool. They made it seem like they invented the pig when all they really did was wipe the mud off its face.

 

Winter mileage suffers due to repeated cold weather startups and extended warm ups which lowers combustion efficiency and absorbs more initial power heating molasses thick lubricants through chill induced tighter tolerances. No amount of motor Vo-Doo is going change the physics.

 

​I can not believe that a site this large does not have a string of individuals in refining?

 

​So...now ya know.

 

[SkiDooNick700]

Thanks for sharing. Yea I mean we had some random warm days here in MI this past winter and my MPG on the DIC Last 25 Miles on those warm winter days (50-60 F) read 17-18MPG, nearly identical to summer time on the same route.

[Cowpie]

Molasses thick lubricants? You mean the 0w20 that is going in the newer car and 1/2 ton engines which meets the industry standard of less than 6000 cSt viscosity at -35c? Just as a 0w30 will. Engines do not have all that tight of clearances (not "tolerances"). They are just more uniform clearances than in days gone by. The tightest is around .004 inch and that is much larger than the thickness of even a 50w oil. A micron is .00004 of an inch. Even 50w oils will filter thru bypass filtration that eliminates particulates in the oil down to 2 micron. So even a 50w oil is smaller by several thousandths of an inch than the tightest clearances in a modern produced engine. Now a 50w is pretty "slow" at extreme cold temps than a 20w. And that is what viscosity is... the resistance to flow, not the thickness of the oil.

[Grumpy Bear]

Molasses thick lubricants? You mean the 0w20 that is going in the newer car and 1/2 ton engines which meets the industry standard of less than 6000 cSt viscosity at -35c? Just as a 0w30 will. Engines do not have all that tight of clearances (not "tolerances"). They are just more uniform clearances than in days gone by. The tightest is around .004 inch and that is much larger than the thickness of even a 50w oil. A micron is .00004 of an inch. Even 50w oils will filter thru bypass filtration that eliminates particulates in the oil down to 2 micron. So even a 50w oil is smaller by several thousandths of an inch than the tightest clearances in a modern produced engine. Now a 50w is pretty "slow" at extreme cold temps than a 20w. And that is what viscosity is... the resistance to flow, not the thickness of the oil.

 

 

You must be a diesel guy. I have never set up a gas motor that loose. Neither do manufactures .004” on a rod? Lifter bore?. Wouldn’t hold oil pressure with a factory pump. Race motors may be .0035 on a main.

Piston clearances on modern motors is under .002”. Some under .001” (coated hypereutectic castings) They are in fact tighter that yesteryear.

Thickness, really? A word, by the way, the world at large identifies with viscosity. Yes even though it is technically incorrect. I was asked to dumb my writing down and now we are going to have an issue with that too?

Your picking fly sh*t out of the pepper shaker.

0 W at 0F is about as thick as luke warm honey. You are right that viscosity is a measurement of a flows resistance. Let’s think for a minute how warm honey would resist flowing through a thou of piston clearance or a wristpin vs water. 20W is about water resistance at 220F.

Don’t think so. You don’t need a Brookfield to find out. Put a bottle in the freezer overnight and pour it out in the morning.

It is RELITIVE anyway. It is just plain thicker and harder to pump in the winter RELITIVE to summer. Have a nice day.

[Cowpie]

RELITIVE or relative? Maybe you took your asked requirement of dumbing down your writing for others to an extreme that even spelling was affected.

 

Oils are rated on cold flow. 0wXX, 5wXX, 10wXX, etc. Irregardless of whether the base oil is conventional or synthetic, as long as the temperature is in the range of the motor oil rating it is non issue. Like I stated, many of those so-called freeze test videos will take the temps down to below the cold flow rating of the oil to exaggerate the differences between oils. A 5w20, 5w30, and 5w40 will all flow well at -10F, as they have a 5 winter cold flow rating which means none of them exceeds the maximum CCS allowances for -30c / -23F. I see many of those freeze test videos taking temps down to -40F, well outside the cold flow rating of even a 0w20 motor oil, which is -35c/-32F. At those temps, one would be advised to do what we did in Alaska... run oil pan warmers. Problem solved!

 

A 20w is resistance (viscosity) of water at 220F? Hardly. At 100c / 212F, water has a kinematic viscosity of 0.31 cSt. At the same time, a 20w oil will have a kinematic viscosity of 8.5 cSt. Over 1000% higher viscosity than water. A 30w will have a kinematic viscosity of roughly 11 cSt, only 30% more than a 20w. And both the 20w and the 30w, with the same cold flow rating, will flow the same at the same cold temp. If 20w had the same viscosity of water at 212F, your engine would grenade pretty quickly. And a 0w20 or a 5w20 have the same 8.5 cSt viscosity at 212F. Only the bottom end cold flow rating is different, and then, only a 5c difference in temp while meeting the same CCS cold flow viscosity.

 

It is true that it is harder to pump in winter than in summer, but the difference is not really as extreme as you would portray it. Only if the ambient temperature is below the rated cold flow temp of the motor oil does it become an issue. And most folks, unless they are morons, do not start a cold engine that has been sitting all night in sub zero temps and redline it at full power under load. So the oil flow when cold is not nearly as critical. Hydrodynamic lubrication is not as critical in typical start up as it is during full load on the engine.

 

We can quibble over engine component clearances, but still the tightest clearances in the tightest engine is still several thousandths of an inch larger than even a 140w gear lube, let alone a 20w or 30w oil. .001 you mentioned is considerably larger than 1 micron which is .00004, and oil will still flow thru a 1 micron filter.

 

On the honey viscosity thing at 0F..... typical honey has a viscosity of 10,000 cSt at average room temp. A 20w oil will have a viscosity of around 50 cSt. And honey at 0F will be a frozen block, as it is primarily of water base. Actually, a 0w20 has half the viscosity at -35F as honey does at room temperature.

[txab]

[Grumpy Bear]

Whatever...this just does not matter enough to argue over. Put your popcorn away. I'm sure decades of experience can be trumped by a 15 minute web search anyway.

[Grumpy Bear]

Idiom, turn of phrase, manor of expression, aphorism. Luke warm honey isn’t a scientific term it’s a figure of speech. To quibble a value is senseless. It wasn’t meant to have one. I will not do irrational debate.

 

Bottom line. Winter driving in a climate like Northern Illinois will increase fuel consumption 15% to 25% depending on your personal routines/habits and it is in fact this high and it is not a function of witches brew fuels. It is exactly as dramatic as I note and exactly for the reasons noted.

 

This is information. Anyone believing it or not is irrelevant to me. I didn’t write this for anyone’s approval.

 

Information is a gift. It can be accepted. It can be rejected. It can be ignored. It can be laughed at. It can go unnoticed. I don’t really care. It has no effect on me or my equipment. I use it, I value it, it serves me well. I’m not the guy getting 70% of the EPA average fuel consumption. I’m the guy getting 20% better. You do with it as you wish.

[Cowpie]

Several days later and it just stuck in your craw that you had to keep it going.

[Grumpy Bear]

Several days later and it just stuck in your craw that you had to keep it going.

 

James 1:19,20 : Know this, my beloved brothers: Everyone must be quick to listen, slow to speak, slow to anger, for man’s anger does not bring about God’s righteousness. (NWT)

 

​Wise advise I take seriously. Words carefully chewed don't get stuck in ones craw my friend.

[Jsdirt]

I think this is regional, because everyone I know, regardless of what they drive, and every vehicle I have ever driven gets worse mileage in winter around here. Was always minor, but starting about 11 years ago it became significant enough to really notice. Sure, some of it is due to the higher density of cold air - computer is going to add fuel to match, but prior to 2006 it was never this bad.

 

That timeframe happens to coincide with the switch from MBTE to ethanol, so I'm sure that has quite a bit to do with it too. Same time that everyone and their brother's boats & outdoor power equipment suffered a myriad of fuel related failures - fuel tank delamination, carburetor clogging and corrosion, meltdown of 2-strokes due to lean mixture from ethanol, etc, etc, etc ... Was an excellent time for me to get out of trucking and into small engine repair.

 

Leave it to the $#%#ing government to put something made for DRINKING in our friggin fuel supply, and give us no alternatives (MA).

[sdeeter19555]

Oxygenated fuels?

 

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[Jsdirt]

I went off on a tangent there ... but I think this part of the country (MA in particular) screws with the fuel alot more than the OP stated.

[sdeeter19555]

I went off on a tangent there ... but I think this part of the country (MA in particular) screws with the fuel alot more than the OP stated.

Oxygenated fuels...while I agree with his "at rack" assessment (my father work for Pennzoil for over 30 years, not the first time I have heard it), I think they do something else (at least in the Philadelphia area), and call it "oxygenated" to further reduce emissions.

 

I know my old gutless beater Outback would drop almost 5mpg in the winter, in one tank of gas to the other and would rebound the same way every spring. Had no bearing on outside temperature, and it was an obvious change from the previous tank to the new tank of fuel.

 

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[Jsdirt]

I notice the same thing, but at around 3 mpg in our 24 & 31 year old vehicles, both FI.