Re: Engine break-in oil

[Simon Favre <simon@domain.elided>]

Peter Pleitner wrote:

>Expert advise and insight requested:  Is there an engine break-in oil on
>the market?  The reason I ask is my belief that the EP (extreme pressure)
>additive in modern SAE rated motor oils (detergent and non-detergent) is 
>not necessarily desirable for rapid and best seating of piston rings in
>rebuilt engines.  I used to be able to find light weight oil with no EP 
>that I'd use for the first 200 miles or so of low load and full rpm range 
>break-in. Naturally I make liberal use of cam lubricant paste during 
>assembly.  Then I'd change to a light weight EP oil for progressive 
>higher load driving to 500 miles.  Now I can't find oil without the EP 
>additive.

Peter,

I think you're confusing additives. There are no EP additives in motor
oil. EP is a designation specifically used for hypoid gear oils. What
you have in typical motor oils is detergent. Back in the good old days,
when rebuilding an engine cost about $150 in parts, engines were broken
in using non-detergent, single weight oils. SAE 30 ND (non-detergent)
was the most common. Nowadays, this is seen mostly as an old wive's
tale. What people do today, is either break the engine in on the oil
they intend to run, OR, they run it in on a conventional petroleum oil
and switch to synthetic only after a full break-in. I would ask for a
recommendation from the company that made the piston rings. Breaking
the engine in on a conventional 10W30 with frequent changes is probably
as good as anything.

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