Pingin'

[Andrew F. Gunnesch]

On Jan 17, 11:52am, David A. Cooley wrote:
> Subject: Re: Pingin'
> At 11:27 AM 1/17/99 -0500, you wrote:
> >With coming into a '85 turbo EXP (w/ a turbo leaking oil into the intake
side)
> >the car had EXTREMELY bad detonation.  When I repaired the turbo (stopped
the
> >oil leak) the detonation went away (and all that blue smoke :) ).  I've
heard
> >that oil in the air/fuel mixture causes detonation and I'd like to know why?
> >Any intelligent answers out there??
>
> Oil is of an extremely low octane (if used for fuel).  when the engine
> starts sucking oil through the intake, it is mixed with the air fuel
> mixture effectively reducing it's octane rating.  Even though you may be
> running gas with a 93 rating, with enough oil you may be down to 80...
> Like mixing kerosene with your gas... it lowers the octane.

I had the exact same sort of problem...  inadvertently damaged an intake
valve stem seal.  Engine sucked lots of oil.  Bad knock sensor too, so it
sounded like I had a can of marbles shaking under the hood when I got on it.

Replaced the bad knock sensor and redid the valve stem seals and everything
is running great with the car now.