Hydro-Treated Oil 1

I'll take a "crack" at it. All lubricating oils begin life as crude in the ground. It is pumped out of the ground, shipped to a refinery where it undergoes certain processing. Each step adds cost, but allows more carefully controlled properties for lubricating.

Crude oil is made up of 'polar' components that contain nitrogen and sulfur atoms, and hydrocarbons that contain only hydrogen and carbon. The first processing step is separation of the polar parts from the hydrocarbon oils in a step often referred to as solvent extraction. This gives the least expensive type of oil used in lubricating. (API group I)

Just as with fats that we eat, the solvent extracted hydrocarbons contains chemicals called "saturates" and "unsaturates". (The difference is that with lube oil it is the saturated compounds that are the most desirable.) The second processing step involves "hydrogenation" (just like with edible fats), in which extra hydrogen is added to the molecules to make them more "saturated". This second step can be done several different ways- hydrofinishing, hydroisomerization, hydrocracking, or severe hydrotreatment, which produces progressively better oil at progressively higher cost. (API Groups II and III) Note that all of these categories could be referred to as 'hydro-treatment', so you don't know where on the scale the quick lube's oil falls.

A third step can be done, loosely called synthesis, in which the lube oil molecules are broken down to simple building blocks and they are then put back together to have the best properties available, but this process is the most elaborate and expensive. (API groups IV and V)

What the quicklube is trying to imply is that they offer a better oil than the most basic, yet not at the price of a full synthetic. The catch is that with specifications going up every few years many oil manufacturers are having to upgrade from Group I basestocks just to meet them, and so without more information it is hard to know if the quick lube is making a distinction without a difference. Ask the manager whether they are using API Group II or Group III basestocks and see if he/she gives you a blank look- if they do I wouldn't read much signifigance in their hydro-treated claim.

Motor oil performance depends, of course, on the base oil carrier (API groups I to V). However, the additive package formulation is of utmost importance and reputable oil suppliers take care the oil containers (metal or plastic) should carry the "donut" and "starburst" symbols meaning you are buying quality oils that meet the requirements set by the API.

This came from a different source, see what you think:
Here is the official description of this type of oil:

Hydro-Refined and Hydro-Isomerized Mineral Oils-
An alternative refining process, which substitutes deep hydrogen treatment for solvent extraction, can yield VI of over 100. An additional advantage of this approach is that such processes can increase the yield of HVI components from almost any crude. Instead of unwanted LVI components being extracted, they are chemically changed into HVI materials, usually of lower molecular weight. This enables the blender to increase the output of light oils (for instance, SAE 5W-30) for which there is a growing market. In addition to the cracking of large molecules into smaller ones, hydro-isomerization reconstructs cracked waxes into branched paraffins. These structures offer excellent low temperature properties. This technology is growing globally to meet global standards for lubricants.

rudyheibert writes:

"Can someone explain in "laymen's" terms what this is? A Drive-thru oil-changer in town adverises that he has this ""Hydro-treated" stuff."

In addition to drwebbs accurate comments, almost every
non-synthetic lubricating oil base stock made which meets
the API minimum standards for quality has some fraction of
it, or, possibly all of it that undergoes some form
of "hydro-treating" during the refining process. So, it's
a confusing and misleading way of blowing a lot of smoke
but really saying:

"HEY EVERYBODY, . . . WE'RE NO BETTER THAN ANYONE ELSE
WHO MEETS MINIMUM ACCEPTABLE QUALITY STANDARDS!"

(as long as the oil filter they use meets current OEM
(Original Equipment Manufacturer) specifications and the
oil they use meets current API (American Petroleum
Institute) specifications and is the proper grade and
viscosity for your application which you should confirm
prior to signing the work order and verify prior to driving
your vehicle off their property) Sometimes you don't even
get what you pay for. Lovely isn't it?

Hope this helps.

Chumley