Date:         Fri, 3 Mar 2000 16:37:48 -0500
Reply-To:     David Beierl <dbeierl@IBM.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@IBM.NET>
Subject:      Re: Which gas??
Comments: To: John2M@AOL.COM
In-Reply-To:  <48.25d2ed4.25f17ef4@aol.com>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 03:47 PM 3/3/2000 , John M. Moore wrote:
>everyone using?  Is it necessary to use 92 octane at $1.55, or is it ok to
>use 87 octance at $1.35?

Er...*If* one can believe the Vanagon operating manual (a dubious
proposition, I guess, given all the discussion about what weight of oil to
use), regular-grade gas is perfectly satisfactory for the V'gon.

For a non-knock-sensing engine like ours, there is only one consideration
strictly concerned with octane number:  If the engine does not knock, you
can use your present or a lower grade.  If it knocks, you must use a higher
grade (or fix the misadjusted timing, carbon deposits, whatever).

There are other considerations not directly to do with octane: Are there
enough high-volatiles for easy starting, is the vapor pressure low enough
to avoid vapor lock when hot-soaking in hot weather, and is the detergent
package sufficient to keep the injectors clean.  None of these can be
answered simply by reference to octane number, but in general the answers
are yes, yes (the Vanagon fuel system is highly resistant to vapor lock, as
all fuel in the engine compartment is pressurized even while engine is
stopped, and cool fuel is constantly circulating through the system while
the engine is running), maybe.  Some years ago it was the case that
lower-octane gas tended to have insufficient detergent for long-term use in
fuel-injected engines, but now that these engines are common I believe this
situation has been largely addressed.  In any case, list members have
generally found that regular use of Techron fuel-injector cleaner (once or
twice per oil change) is useful.  Volkswagen also has their own brand of
injector cleaner which they of course recommend and which very likely costs
the earth.

david
David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"