<VV> awl

[Padgett]

>Pag,  Multi-vis oil is NEVER  thick......the top number shows that LAB
>testing shows that it "PROTECTS"  as well as 50 wt  oil that is the same 
>temp.

Huh ? My SAE books show measuring viscosity *ranges* at two different 
temperatures  - "W" (Winter)  at -18C in centipoises  and in centistokes 
at  100C. The lab tests are ASTM D 2602 for W and ASTM D 445 for hot.

Incidentally at 100C,  50 weight has 4-5 times the viscosity (drag) of 30 
weight).

In conventional oils this is achieved with a straight weight base and 
adding long chain polymers to modify the characteristics. These break down 
in time into not-so-long-chain and the oil approaches an intermediate value 
straight weight. Before I got deep into 3800 engines (the georotor oil pump 
has different characteristics) I used to be able to tell when it was time 
to change the oil by a 2-4 psi drop.

Synthetics can be (not saying are) much more stable. I am just starting to 
try some of the new blended oils but so far am not particularly impressed. 
Of course if crude prices go high enough, synthetics may turn out to be 
more economical.

The SAE is celebrating its 100th anniversary this year. My books are not 
quite that old.

Padgett