hi.
GL-4 is better for shifting and syncronizers.
GL-5 is better for preserving gears ....like the ring and pinion gear.

your NAPA store must not be too savvy.
I am holding in my hands a white plastic qt bottle of gear oil. NAPA brand,
in big letters.

it says ....NAPA Premisum Performance Gear Oil, SAE 85-90,
API Services GL-5, GL-4, GL-3.

or, the commonly available GL-4 synthetic gear oil that many vanagon owners
use Redline MT-90.
I like that with some Prolong Gear Oil addtive in it.

I don't surface every flywheel I see . It 'depends.'
Was it you that asked about rear main seal and pilot bearing also ?
the pilot berings on waterboxer vanagons are the part that usually fails
first, even fairly commonly, in my experience.

Scott
www.turbovans.com

----- Original Message -----
From: "Kurt Grotz" <kgrotz@CRAFTECH.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Sunday, May 09, 2010 2:02 AM
Subject: GL-4 or GL-5 Tanny Oil - HELP?

>I have been getting mixed messages about the proper oil to use.  Some say
> only GL-4 some say they use GL-5 just fine.  Problem is - I can't find
> straight up GL-4 in any auto supply store.   Thoughts and or ideas?    And
> is it SOP to resurface flywheel and replace seal when tranny is removed.
>
> Thanks