<VV> RE: y'all

[Jim Burkhard]

The statements below often are not true for at least some multi-grade
synthetic oils... Often, at least the reasonable range (say 10w-30)
synthetics don't require *any* viscosity index improvers to meet the
viscosity specs.  This means a higher fraction of oil & fewer additives to
break down... Even for the wider ranges (15W-50, etc.), they probably
require less addition of VI improvers than same-range mineral based oils.  

This is nothing new, either... AMSOIL was like this at least 20 years ago
and I'm sure others are/were as well. This is one of the big advantages of
synthetics.  IMHO, if your Corvair doesn't leak or burn like mad, you oughta
have synthetic in it.  And, if you've got a turbo Vair and aren't running
synthetic oil, you truly need your head examined.  The turbo bearing oil
gets *really* hot especially on a soak, and normal mineral-based stuff will
coke up much more readily than a good synthetic. What does the engine cost
compared to oil?  Sure lots of folks have all kinds of anectodal evidence of
engines going 200K on mineral oil, but there's no science in such numbers --
that same engine might have made it to 250K or 300K on the synthetics.  Or
maybe you your turbo wouldn't have needed that last rebuild...  Who knows?
Leave such conjecture to the research labs of OEMs and other sin industry
who have actually performed such evaluations.

Also, I've noticed some misuse of terms by some posters. "Synthetic blends"
are only a part synthetic-part mineral base product.  Who knows whether you
are getting 50:50 or 5:95? IMO, They are a dumb idea...  If you are going to
pay for expensive oil, pay a little more and get full sythetic instead of
5%/10%/50%/lordknows%. Yeah, I know all "100% synthetics" aren't the same,
but one thing at a time.

As for the naysayers... More and more OEMs are factory-filling and
specifying full synthetic oil on their high performance engines.  This is
typically Mobil 1, but that's probably at least partly because it is readily
available. Trust me, the last thing an OEM wants to do is spend extra ~$10
per engine filling with expensive oil.  They whine, stamp their feet, and
twist their suppliers' arms over *pennies* on components.  Factory-filling
with Mobil 1, makes beancounters really gulp, but it's happening more and
more. This oughta make you think a little in at least using it in tough
applications as well.

Jim Burkhard


> Maybe the oil companies are doing things differently now, but 
> when I cared 
> about this stuff ten years (or more) back I researched the 
> specs.  (mostly 
> Quaker State and SAE).  The multigrades didn't have different 
> weights.  As someone 
> else said, the oil manufacturer added long chain polymers so 
> that as the oil 
> reached operating temperature it wasn't any thinner that the 
> target viscosity.  
> So a 10W-30 wasn't any thinner than a 30 weight at operating 
> temperatures.  
> The problem is that shearing and other wear factors "cut up" 
> the long chain 
> polymers and you didn't keep the higher viscosity as time 
> went on.  I know there 
> were other qualifications, but the primary target was 
> viscosity and wear 
> characteristics at operating temperature so you could have a 
> year round oil.
> 
> Bob Hall