Re: Mobil 1 & Semi-Synth

[Michael Murphy <mmurphy@nais.com>]

Todd Phenneger wrote:
> Has anybody tried Castrols new  Semi-Synthetic oil.
>         It is about $2.25 a quart or so and is apperently 1/2 synthetic
> and 1/2 dino oil.  Seems a little odd to me.  Maybe a hoax but it is a
> well known company.  Maybe it would protect better than dino fluid without
> the leak problem associated with putting it in an older motor?

Todd,
I sent email to my brother (one that works for Mobil) asking about,
among other things, a more detailed answer to his comment about blended
oils, other than, "...kinda defeats the purpose...".  From what I've
learned, dino has refining byproducts and "poorer" lube properties that
the synths don't have. So what's the point of blending them, other than
pricing?  Better, how can a blend oil not have the dino part break down
faster than synth part? If primary goal is to lube engine better/faster
it seems like your getting exactly what you're paying for - half the
lube benefits at half the price.  BTW, Mobil specifically warns against
possible incompatibilty if Mobil 1 is mixed with other synth oils.

The leaking gasket/seal business is an admitted but not much publized
downside of the synth products.  My conclusions, YMMV, re: leaking after
changeover to synth (Mobil 1 in my case). Data points were collected on
5 cars (1 new, 4 used) with changeover after vehicle purchase (data on
gaskets only, had no seal/other failues):
1. If the gasket is good, synth won't make them leak.  The 3 leaks that 
   occured (1 on new, 2 on used cars) were, in the end, attributed to 
   failed gasket material.  Detergent action of the synth most likely 
   cleaned whatever deposits were masking gasket failure on used cars.  
   BTW, I've asked my brother to elaborate on Mobil 1 reformulation in 
   early 90s had anything to do with additive (detergent) package.
2. Good maintenance on dino=less deposit buildup=leaks appear sooner (in 
   already failed gasket material) than poor maintenance (more deposits 
   to break down).

Confused?  I think that's what they "the marketers" want.
MJ Murphy