<VV> Which Oil

[Smitty]

Smitty Says;  I'm afraid I have an opposing opinion to to a lot of what has 
been said here.  In the first place there is no break in required on modern 
engines because of the precision fit of mating parts.  They can put 
synthetic oil in them from day one with no problems.  If you ever read the 
test procedure for modern engines it goes something like this.  Fire the 
engine up from stone cold and take it straight to 6,000 rpm.  Run it that 
way with restricted controlled coolant until the oil reaches 300 degrees. 
Bang, shut it off.  put it in a deep freeze environment till the block 
reaches minus 15 degrees.  Fire it up again straight to 6,000 revs.  Repeat 
the process 7 to 10 times.  Tear it down and admire their engineering skill. 
Don't expect your Corvair engine to handle this kind of treatment.  Just be 
aware that you can't talk about oil in modern engines at break in time when 
you are talking about your Corvair.  That's apples and oranges.
Now for a couple of opinions.  The reason for the gruesome cross hatch in 
the cylinders is not especially good for your engine.  Back in the day and 
even now people believe you have to do that to get a break in.  Bull 
feathers.  It reason for it is that mechanics learned way back that if they 
used a fine hone even in a straight round cylinder that the guy whose engine 
overhauled would be back in about a week bitching up a storm because his 
engine was showing smoke at the tail pipe.  Maybe he would want to give the 
mechanic the benefit of the doubt an wait a month before he really got bent 
out of shape.  If he were patient it would eventually break in and he would 
have beautiful cylinder walls with perfect fitted rings.  Mechanics soon 
learned that they could avoid the problem by making a very aggressive finish 
on the cylinder walls and the rings would seat very quickly.  The fact that 
they were filling the crankcase with steel grit and reducing the life of the 
engine by 20,000 miles didn't bother them a bit.  The customer was happy.
I have yet to build a smoker I use a 220 grit Sunnin hone to square the 
cylinder.  Then I reverse the hone from end to end in the cylinder two or 
three times with the lightest cut I can get without chatter to break off the 
high spots on the ridges.  That's it. And it's not going to smoke.  I have 
some other sacred cows to step on the toes of if you are interested.  Just 
remember, this is my opinion.  It may be backed by 60 years of engine 
building but it is still an opinion and you are welcome to yours.