[R-390] Synthetic Oil

[Charles Steinmetz]

Tom wrote:

>I was taught early on that when lubing a "sleeve bearing" motor to 
>always use non-detergent, as the detergent additive would "glaze" 
>the sleeve bearing and cause premature wear.

I have heard this, but I started using Mobil 1 for almost everything 
more than 35 years ago and have never seen this problem (or any 
problem, for that matter).  I have a window fan that runs 24/7 from 
(roughly) March to November to cool the attic.  Before Mobil 1, the 
sleeve bearings needed lubrication 3 or 4 times per season.  I used 
M1 on it way back then, and I think I may have relubricated it 3 
times since (about once per decade).  Most of the sleeve bearings I 
have lubricated with it have *never* been lubricated again.  So 
whatever the theoretical problem is (or perhaps it was an empirical 
problem that was wrongly attributed to detergent), there does not 
seem to be any problem in practice with M1 motor oil (I can't speak 
for any other products).

Detergent keeps tiny metal particles (worn off of beaings) suspended 
in the oil, while non-detergent oil lets them settle out.  In a 
splash-lubricated gearbox or crankcase (for example), we use ND oil 
to let the metal dust settle to the bottom of the sump where they 
don't constantly circulate through the bearings.  With pressure 
lubrication (car engine crankcases, for example) we filter the oil, 
which removes the suspended metal particles, so we can use detergent 
oil without suspended metal particles being a problem.  In a typical 
sleeve bearing installation, there is no sump and no place for metal 
dust to fall out -- there is only the oil between the bearing 
surfaces -- so there is no disadvantage *from this source* (suspended 
metal particles) to using detergent oil.

Best regards,

Charles