Miata Mailing List: September 1993, Message #80
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   From: Herb Samuels 
Subject: Re: Lifters
   Date: Fri, 10 Sep 1993 14:02:02 -0400

Jim:  The Miata manual states that the lifters may make noise for less
than 10 seconds and that it is normal.  I don't really buy that.  I
have a 1990 and did not notice that problem until about 9 months ago. 
I have had my oil changed at the Dealer and noted that the Dealer
changed the brand of oil  they used when I noticed the lifter noise (oil
was 10w-30).  Mazda has recently notifed Dealers to use 5w-30 if
lifter noise is a problem.  Also Miata Magazine indicated that for
those cars with lifter noise with lower viscosity oil that Mazda has
replacement lifters with somewhat larger passages.

My feeling is that the Miata should use the highest grade oil since the
engine is frequently run at high RPMs which might tend to result in
oil breakdown.  For the last 9 months I have run synthetic oil in the
car, first Castrol Syntec (5w-50) and now Mobile I (5w-30).  I do not
hear any lifter noise even if the car has not been driven for a week.
I think that the message is that although Mazda may consider some 
transient lifter noise as normal, I would try to prevent it from
happening  since the lifter noise may reflect a decrease in
lubrication at startup which might affect other parts of the engine as
well.

Herb Samuels