Wouldn't it be easier to compare viscosities of single grade oils, also not
sure why you would use a motor oil to lubricate non-combusting machinery,
you're getting a ton of additives along with some viscosity ranges suited to
temperature extremes that seem to me anyway, inappropriate to lubricate
machinery.

"Michael Koblic" wrote in message
...
LMS recommends Mobil 1 for lubricating mini-mills. I picked up a bottle of
5W-30 and have been using it. I noticed that the oil does not stay on the
dovetails very long and tends to pool on the bench.

In my simple mind I thought: Higher viscosity is needed, something like
20W or so. That is where I got confused: I looked up the figures for
Vactra 2 (being the industry standard for ways etc.). Its kinematic
viscosity at 40 deg C is 68 cSt (ISO68). When I looked at the 5W-30 the
viscosity was almost exactly the same. I thought this might be an error on
the Mobil page but no, a similar result came up for 5W-20. To puzzle me
further, the 10W-30 is somewhat thinner at this temp.

The tables at my disposal suggest that the 5W oils should be under 20 cSt
at 40.

Before all this I bought a bottle of 15W-50 which was on sale locally.
According to the tables it should be somewhere near 45 cSt but according
to the Mobil product sheet the 40 deg C viscosity is a whopping 131 cSt -
about half way between Vactra 2 and Vactra 4.

What am I missing here? Is this comparison at all valid?

--
Michael Koblic
Campbell River, BC