RE: Vis of 30 vs. 50 Mobil 1

Subject: RE: Vis of 30 vs. 50 Mobil 1
From: Jerry Stadulis <73621.2717@domain.elided>
Date: 20 Sep 96 07:46:28 EDT
Prakash,
 
 > What I also intend to do at the next oil change is test a sample 
 > of unused Mobil 1 10W-30 oil just for control purposes.
 
That's an excellent idea.  If you remember, post it to the digest so we can 
see how the vis (and contaminants) compares with your sample of used oil.
 
 > Synthetics seem to be usable over a wider range of temperatures 
 > and that's probably why the oil shows up as a 40 grade oil at 
 > 100degrees Celsius.  I don't know, just a guess.
 
No question that the vis is less affected by normal temperature changes than 
for a petroleum oil.  (The paraffins in petroleum oil are the primary 
constituents that cause the vis to change with temperature.)  I just had 
another thought since you mentioned you had been consulting the BMW recs for 
oil viscosity...  Were the viscosity specs for the various grade oils you 
posted _BMW_ specs for used oil, or were they API specs?  That could explain 
why the oil labelled as a 30-weight met the criterion for a 40.  Sounds like 
it might be interesting for me to drop by the Mobil 1 web page.
 
 > Also if anyone is interested in taking a look at the BMW Service 
 > Information Bulletin regarding their recommendations on oil 
 > viscosity here is the number:
 
Is this something you could post to the FAQs?
 
BTW, how (with whom?, mail order?) do you get your oil tested?  What does it 
cost?
 
 Regards,
 Jerry
 Arlington, TX (20-Sep-96, 06:15)
 '95 540i-6 spd