Michael Koblic wrote:
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?



Automotive detergent oil will screw up the felt wicks that are used in
many machines. It will make them stiff and move the oil. Also the
detergent oil will tend to carry the grit in suspension rather than
letting it settle out.

The Vactra way oils have an additive to make the oil adhere to the ways,
the same function as the additive in chainsaw bar oil. Vactra 2 is what
is mostly used on ways.


John