Date: Sun, 4 Dec 2011 12:35:33 -0600
Reply-To: John Rodgers <inua@CHARTER.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: John Rodgers <inua@CHARTER.NET>
Subject: Re: Oil recommendations simplified
In-Reply-To: <BAY152-ds1418FE88BDE90602804156A0B40@phx.gbl>
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Dennis, that is a terrific write-up on Oil. Good to see reasoned
support for 15W50 oils.
Re: Oil Analysis. This is really something worth doing or at least
considering. It truly tells the story. Back in the '60's I worked in an
oil analysis lab for Page Industries, who had a contract with the Army
at Ft. Rucker, AL. Ft. Rucker was the home of the advanced helicopter
training command. Guys trained there were on their way to Vietnam. My
job was to run the oil analysis on all the aircraft used on the base and
that included a whole bunch of helicopters. The lab analyzed the oils
from engines, transmissions, and other oil using systems in the
aircraft.. We developed a highly accurate predictability of engine and
transmission failures - about 93%. A plot was maintained on each
part/aircraft and you could see the curve moving toward parts failure as
measured metals/silica content increased. There was a test program where
a chopper (Huey) was deliberately flown in a sand pit hovering just off
the ground for hours and hours to the point of engine and parts failure,
just to see how far the machines could be taken. The lab plotted the
whole thing through oil analysis. Again we could see the move towards
parts failure as indicated through the analysis.
Oil analysis is worth doing. May increase the life of ones wasserboxer.
Re: Cold Weather Operation. When living in Fairbanks, Alaska the best
protection for ones water cooled vehicle was to have a block heater
installed and preheat the engine that way. Some heaters were inserted
through a freeze plug, and some were tank heaters - but both types
heated the water which in turn circulated via the thermosiphon
principle, heating the block and the oil. If one had to do a cold start
- and indeed could even get the engine started - the engine had to be
allowed to go through a long warm up. If one didn't allow sufficient
time - a person could start down the road and suddenly lose oil pressure
and potentially seize the engine. Piston aircraft are prone to this
problem as well. Saw a number of aircraft that this happened to. In both
ground vehicles and airplanes - the oild forms a hard frozen lump of oil
in the sump. If the engine is not allowed to warm up significantly to
transfer heat to the oil sump - sudden acceleration will drain all
liquid oil (which is not much) out and because that lump is there, there
isn't enough oil flowing to adequately lubricate. And engine failure can
be eminent. The trick is to warm the engine to start, then let it idle
to a warm up - then shut down and wait just a bit. Heat energy migration
will thaw the oil the rest of the way, then the engine can be re-started
and one can drive away safely. Live through a lot of extreme low
temperatures and this was the only way that truly worked. When you fly
airplanes and drive vehicles at temps that are like -35F and lower, you
learn real quick what it takes to operate the vehicles.
BTW - somewhere in my collection of pictures I have one of me doing
chin-ups on a the blade of a propeller on an airplane in Winter in
Alaska. The temp was like -38F -40F. Engine had straight 50wt oil.
That prop didn't budge, even with my feet off the ground and me hanging
there.
John
John Rodgers
Clayartist and Moldmaker
88'GL VW Bus Driver
Chelsea, AL
Http://www.moldhaus.com
On 12/4/2011 9:43 AM, Dennis Haynes wrote:
> The attached chart is what VW offered for most of their models back in the
> day. There are two considerations though. As a left over from the air cooled
> days outside temperature did have an effect on the running oil temperature.
> In fact overall engine temperature was effected by outside temp. I once
> drove my 72 bus 400 miles and the oil temp never got over 120F. With the
> water cooled engines except in extreme conditions the oil is going to at
> least get as hot as the coolant and then some more depending on speed and
> load. The other consideration is that the multi-range oils of the day did
> not maintain viscosity well and often were not even stable. The science then
> was nowhere as good as it is now.
>
>
>
> There are two major requirements for oil viscosity. The most critical to
> select is at start up. At the lowest temperature expected not only does the
> oil have to allow the pistons to move at allow the engine to start, it has
> to flow, be able to splash, and the pressure relief valve has to handle the
> excess flow. As such the low temp ranges indicated on this chart are still
> good. You do not want straight 40 oil at low temps due to start up concerns.
> Things that happen with too heavy an oil at start up include cylinder
> scuffing and wear, excessive oil pressure resulting blown oil coolers and
> seals, locked-up spun bearings in the case and I have even seen the oil pump
> drive tab sheared off. When we get extremely cold weather here on Long
> Island I see many cars loose the crank and cam seals form them actually
> getting pushed out from excessive oil pressure since the drains just can't
> take it when folks start it up and drive without letting some warm up. On
> the other end of the spectrum the oil has to maintain some minimum viscosity
> at the highest bulk temperature to maintain film thickness for the bearings,
> avoid washing past the rings, and maintain sufficient pressure. Here is
> where the VW boxer engine, (both air and water cooled), need some attention.
> These engines are really loose tolerance, that gets even worse as the case
> expands and bearing clearances increase. To make matters worse the pump is a
> simple design that also gets affected by expansion and there is very little
> reserve. Then we need to run them close to 4,000 rpm and load them
> continuously really driving oil temps up. Overfill the crankcase and some
> other factors and it is possible to see oil temps of 250F or even more.
> Thankfully we now have multi-weight oils that actually work.
>
>
>
> SAE oil viscosity for straight weight oils is specified at 212F. For the
> multi-weights the lower number is @104F and the upper is still at @212F.
> This gives little indication of what the oil may actually be at extremes
> like -10F or 300F. If we look at the product specs for these oils you will
> see that @212F (where our oil should be),a straight 40 will be thinner than
> at 15w-15 or 20w-50. So for us this is the better choice at both start up
> and running for most temperatures. Now note the 15w-40 or 15W-50 is good
> down to almost 0F. Synthetics with these same ratings can go down even
> lower as they have very low pour points. So for most of us the 15w-50 is the
> ideal oil for most conditions. Do note that in extremely cold weather after
> start let it run for just a minute or so to get some heat in the oil and
> drive gently and avoid revving the engine more than needed until you see the
> temp gauge start to move or you feel some heat.
>
>
>
> Most engines do not need the high viscosity oils. For the in line VW engines
> the 5W-40 or 0W-40 oil works just fine. Most modern vehicles now even use
> 5w-20 or even 0W-20 oils. The vanagon won't like that stuff for long.
>
>
>
> As for how often to change oil there are a lot of variables. The only way to
> know is to do oil analysis. This is best done at the expected half-life of
> your oil change interval. So VW recommended changing at 7,500 mile intervals
> for both regular and synthetic? So at ~3,000 miles take a sample and send it
> in. Be sure to keep the sample clean. The good test programs have pumps and
> tubes and stuff to help you get a clean sample. Taking one out of the drain
> pan is not good. The test results will tell if the oil needs to be changed
> and why. Is it contaminated with dirt, fuel, coolant? Are there excessive
> wear particles? Are they ferrous or tin/lead/copper, etc.? Is the oil itself
> actually breaking down? Loss-Gain of viscosity or nitration? You may need to
> do some interpretation and the lab will help if needed. Yes there is a cost
> to this but I have saved many engines over the years due to detecting things
> going wrong before the failure. Coolant and silica are the biggies.
>
>
>
> As for synthetics being worth the extra money there is no doubt that
> conventional oils are getting better and do a really good job. The
> synthetics though are a premium product and even if the only benefit was
> using them for longer periods the cost is offset. For our engines the
> increased temperature range is a real benefit.
>
>
>
> Dennis
>
>
>
>
>
> http://www.thesamba.com/vw/archives/manuals/1985vanagon/56.jpg
>
>
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