Date: Sat, 10 Apr 1999 11:05:39 -0400
Subject: More on Oils
From: Chris L Johnson 

>From: Andreu Codina 
>To: 
>Sent: Monday, April 05, 1999 12:41 PM
>Subject: Re: Bultaco Tech. Support Enquiry
>
>It depends on how you want the clucth, if you like agressive clutch, 
>use the ATF, but I personally recommend for Bultaco owners Valvoline 
>10W40 or 10W50.
>
>Best regards,
>
>Andreu Codina

The above illustrates what I was saying in the other e-mail on Dexron,
how the thinner oil will create a faster response.  It also illustrates
how design will affect how the clutch responds with respect to the oil
used...that one should not assume one oil is best for all bikes.  My
Scorpa does not function well at all on motor oil, for example.  Motor
oil makes the clutch drag, the tramsission shift notchy as a result, and
the engagement of the clutch is too slow.  According to Andreu (and he
knows), the Bultaco can tolerate higher viscocities without drag.

One needs to experiment with oil to actually feel what happens to the
clutch action...to assess clutch engagement characteristics as a function
of oil viscocity and amount at both cool and hot temperatures.  The
thicker the oil, the greater the potential drag and the slower the hit on
quick engagements.  The thinner the oil, the faster the engagement and
there is less tendency for drag.  If too thin the clutch can be grabby or
chatter, especially when the bike gets really hot.  Once you understand
what affects what, you will know what to do.  Too much oil will also
increase drag.  Sometimes less-than-recommended oil will really help.  I
have been using 400cc in both my Gas-Gas and my Scorpa, for example.  If
I go by the overflow check hole on the Rotax motor in the Scorpa, I will
fill to something like 700cc!

As I have often written, selecting oil is not made easier by the very
confusing marketing of oil by SAE viscocity range number instead of
actual viscocities...and that the SAE viscocity ranges for gear oil are
not the same as motor oil! Actual viscocity is quite another thing!  As
you will note below, there is a BIG difference between motor oils and
Dexron ATF.

The below is a re-post the results of my own, at-home (non-standard)
viscocity tests:

Comparitive viscocities at 60 degrees F with 50cc of oil passing through
a .14 orifice.

Gear Related:
---------------------
Valvoline 50 weight Racing Motor Oil		155s (Great for those hot running,
air-cooled street bikes)
Stihl Chainsaw Bar Oil	 2006			97s		
Valvoline 85W140 Gear Oil			83s
Valvoline 10W40 Motor Oil			57s
Unilube Synthetic 75W-90 Gear Lube		50s
Belray Gear Saver 80 weight			50s
Citgo Chrysler Spec 7176 ATF			41s
Valvoline Dexron III ATF			26s (a great option for eliminating clutch
drag in trials bikes)

Suspension:
---------------------
Bel-Ray High Perf. Fork Oil 10 weight		21s (same oil as 7 weight)
Bel-Ray High Perf. Fork Oil 7 weight		21s (same oil as 10 weight)
PJ1 Fork Tuner H.V.I. 5 wt.			16s
Bel-Ray High Perf. Fork Oil 5 weight		14s
Golden Spectro 85/150 2.5 wt. Very Light	13s (a petroleum/synthetic
cartridge fork oil)
Stock Paioli Fork Oil from Factory, Used	12s
Honda/Showa SS7 shock oil 5 weight		12s
Fox Racing Oil 5 weight J26			12s
Maxima Zero-Fade Light Shock Fluid 5 wt.	11s (white bottle)
Maxima High-Perf. Light Shock Fluid 5 wt.	11s (black bottle)
Stock oil out of a Boge/SACHS shock		11s

Isopropyl Rubbing Alcohol			9s