Viscosity

Society of Automotive Engineers "W" system chart for oil viscosity

Fill up at Mill Valley B-100
$4.15 / gallon
mileage 182070

Its a cold end of March for the Eastern Seaboard, but despite the chill in the air my duties called me to drive to the DC area and spend the day outside with a video camera.

Madeline has been leaving puddles of oil behind her front passenger side tire, and last time she was in to see Dr. Doug he said that she'd at one point run nearly dry of oil.  She takes a special diesel oil, 15W40.  So today started with a quest for 15W 40 oil here in Baltimore.  Checked first at the Royal Farms in Hampden, where the face of everyone standing in line at the cash register snapped in my direction when I came through the door.  You get the feeling that place is the nexus of Hampden's street life.  The Farm Store only had 5W30 and 10W40.

Next, I "excuse me sir"-d the elderly gentleman fixing a screen in the back of Sirkis Hardware.  Same deal,  only 10W40 and 5-something.  Up the street at the Mieneke up the street, the girl at the cash register clued me that i'd have have to go to Advanced Auto Parts at 20th and Howard.

At Advanced Auto Parts, a young black clerk with a fanciful neck tattoo was very helpful.  Turned out that 15W40 is only available in gallon jugs-- $15, please.  I fear that I may actually need that much!  Out in the parking lot, I popped the hood and took stock.  I'd put a quart in a few days ago but thought she might need more.  When I removed the cap to the crank case, there was a steam/smoke emanating from it, and I muttered aloud "That can't be good", which attracted the attention of a large, friendly black man.  I fired up the engine, and we looked at it, determining that it was a head gasket issue.  I didn't add any oil after all, since the dipstick showed "full".  And the big friendly guy assured me i'd have no problem driving to DC and back before getting it fixed.  Then he asked if I was interested in selling the car.  I explained that she was a special case who ran on biodiesel, and that I was documenting my experiences with her.  He looked at me quizzically and walked away.

A little research on why diesel engines need 15W40 revealed that that designation refers to starting temperatures in Centigrade, the number followed by "W" referring to the starting temperature in Winter and the other one referring to starting temperature when its... warmer.  And all that time I thought the W meant "weight".

Turns out the viscosity of various types of oils varies by temperature, and the Society of Automotive Engineers created the "W" system to refer to oils by temperature range.

Green Envy

Dateline: Baltimore, September 2007

     

     For years I have watched with envy as the slightly better-heeled were able to speak their environmental conscience through their choice of vehicle.  Prii (that *is* plural for Prius, isn't it?) appeared on my street.  I saw tiny Smart Cars on the highway.  Scooters zoomed past me in the parking lane while I waited at red lights.  

    Sure, my '99 Subaru was no Tundra or Escalade.  But I longed to do something more about global warming and fuel self-sufficiency than sporting a "Mountainhugger" bumper sticker.

    "Take the bus, take the train" said an inner voice. My daily schedule includes dropping off my son at school, a six mile drive headed out of the city.  Walking to the bus stop with a six year old in tow, waiting for the bus, riding out to "the county" and reversing the process, twice a day was more than I could contemplate.  Plus it would put a 4 hour dent into the 5 hours I have available to do billable work-- I'd be coming home, eating lunch, and walking back out to the bus stop.

    So in the waning months of the reign of Bush II, I decided to do something to really investigate the choices available to people who wanted to fuel their vehicles with something other than petroleum.  Get off the gas grid.  

    What I heard about biodiesel seemed too good to be true.  You could fuel your car on waste grease gathered from your local fast food joint?

    Some research revealed that this option was for people who had the time, tools and talent convert their cars, gather used cooking oil and strain it in their backyards.   Oh, and fill up their trunk with the extra tank that held the Waste Vegetable Oil, start their car using petrodiesel, and store their extra oil on-site. Though I found that admirable, I wasn't quite ready to go there. 

   Then a biodiesel co-op sprung up at a garden center in my neighborhood. Members could go and get the fuel twice a week when the pump was open. That sounded more do-able.  I started researching diesel engines and biodiesel on-line.

     The first thing I learned was that biodiesel is a term applied to many different brews.  The Waste Vegetable Oil option is the cheapest, once you've done the conversion and have the grease source in place.  Otherwise, there's a commercially available product called biodiesel comes out of a pump, pre-brewed.  This is what they had at the co-op.  Despite my aspirations to be completely off the gas grid, this seemed like a doable option, a starting point.

    So as I was doing my regular Sunday morning leaf through car classifieds,  I began to turn my attention to VWs and Mercedes Benzes,  the main manufacturers of diesel automobiles sold in the US.  Having owned two VWs, they have a special place in my heart, but I sensed they wouldn't be mileage champions.  Some Benzes, however, were said to run forever.....

    One day in late September a classified ad caught my eye.