IML: Even more on The old oil argument

["Dick Benjamin" <dickb@xxxxxxxxx>]

I probably should have made more noise about the fact that I live in the
Southern California warm country. We almost never see under 32F.

 I would not be running SAE30W in my worn old collector cars if I still
lived in New Hampshire!  Back there, the multigrade oils were much more
helpful with cold starting.  I recall one morning at -12F that my brand new
56 Plymouth would start and idle, but I could not steer it or shift the
transmission (both manual) until I let the car idle for at least 30 minutes
- so I know what thick oil will do! 

As for protecting from startup wear, there are two factors to think about:
Thinner oil will circulate sooner, but staying on the surface of lubricated
parts is also important, because regardless of how quick the oil starts to
circulate, the first few revolutions of the engine are going to be with just
whatever clings to the cylinder and bearing surfaces.  

I'm not smart enough to know the answer - so I prefer to go with whatever
the designer specified -the only exception is that I believe that 5W30 is
specified for most modern cars to help with higher fuel mileage (CAFÉ), and
I also believe that as long as an engine will last 100,000 miles or so, the
manufacturers are not really concerned with whether it wears out at 150,000
or at 500,000.  Diesel manufacturers are concerned about this, and I note
the Chevy/GMC Duramax Turbodiesel (Made by Izusu) specifies 15W40.

Dick Benjamin

-----Original Message-----
Rob P
Sent: Sunday, December 05, 2004 9:50 AM

First of all, I will have to pull out my owner's manual for the '70.  I just

followed what my Dad did with the car.  I could swear that it had the same 
chart as my newer cars which recommends 10W30, but I usually trust Dick B. 
more than I trust myself.

If you use straight 30 weight aren't you giving something up at start-up? I 
thought the purpose of the multi-viscosity oils was to flow easily at 
start-up, until the car was warmed up and in extremely cold temperatures.  
Wouldn't running straight 30 cause more wear from starting the car cold?

As for the 5W30, it was mainly a fuel economy move.  I believe the front 
wheel drive Mopars recommended it for a year or two and then went back to 
recommending 10W oils, presumably for wear issues. Some people still swear 
by it, others won't touch it or the newer 0W30 synthetics.





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