Miata Mailing List: September 1993, Message #16
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   From: dbk@mozart.esl.com (David Kay)
Subject: Re: synth oil
   Date: Wed, 1 Sep 1993 13:33:58 -0400

Paul Buckingham writes:
> I always thought 3000 miles was the recommended interval
> between  engine oil changes for regular (non-synthetic)
> oil, and that one of the advantages of synthetic oil was
> that you could change it (but  not the filter) less
> frequently for the same effect thus offsetting  the cost
> difference. For those who are changing Mobil 1 every
> 3000.. ... why? Would you change regular oil every 1000 -
> 1500 miles if  synthetic wasn't around? Or is it that
> synthetic oil doesn't last  longer than regular oil? 


Longer drain intervals are a benefit of synthetics, as long as you  
change the filter every 3K.  I use Redline (a synthetic) and change  
my oil every 3K or so, anyhow.  Why?  Hell, I don't know.  It seems  
like the cost of oil is a reasonably low part of the cost of owning  
the car, even at 3 bottles x $7/bottle per oil change, so the benefit  
in engine life can be pretty marginal to have it still be  
cost-effective.  Also, if I let it go to 3500 for reasons of  
convenience, I don't sweat it.

I suppose, though, that part of it is psychological:  I drive the  
engine hard, and this seems like something nice I can do for it.   
Such anthropomorphisms are probably the first sign of senile  
dementia, but it feels good, anyhow.

For what its worth, I use organic oil (Castrol) in my race car, but  
change it every race weekend (say, two hours of engine time).  On the  
other hand, it's a Formula Vee, so it's not a real race engine.

> - the ad that prompted me to consider synthetic oil was for
> something  called " Blueprinted Synthoil 100". The ad was
> in a 1992 issue of  European Car and quoted many extracts
> from auto magazines (VW &  Porsche etc.) upholding the
> claims of the manufacturer which were: 

> 

> (at 55mph)
>
> 11% better fuel economy
> 9% more BHP
> 50,000 miles between changes (equiv to 5000 miles for regular oil)
> Better corrosion resistive properties than other synth oils

The polite way of referring to claims like this is probably "I  
haven't experienced benefits of this magnitude while using  
synthetics."  "Crap" is probably more appropriate.

You'll get marginal benefit in lubrication under high load  
conditions.  Not 10Hp or 11% fuel economy.  Or every auto  
manufacturer would use synthetics to improve their fleet averages.

Whatever you use, just do it.  Change the oil and filter, today if  
possible.  The *most* important factor in engine protection is  
changing oil frequently; that is, every 3K or 3 months, whichever  
comes first.

dbk