Grape seed oil and olive oil are very different in composition. While olive oil is primarily a monounsaturated oil, grape seed oil is primarily a polyunsaturated oil. Despite its more unsaturated nature, grape seed oil, with a smoke point of 485° F, is more stable to high temperatures than olive oil.

Most commercially available olive oils are virgin or extra virgin oils, rather than refined (chemically treated) oils. Virgin oils are comparatively higher in antioxidants than refined oils. By contrast, most commercially available grape seed oils are highly refined and, as such, contain smaller amounts of antioxidants. It is important to note, however, that an unrefined grape seed oil, one that has been cold pressed and not chemically treated, is very rich in antioxidants.

Also, some people confuse grape seed oil with Canola oil. They are very different oils and come from completely different sources.

The shelf life of grape seed oil will depend upon storage conditions and whether or not the container has been opened. To maximize longevity, keep the oil stored in a cool, dry place. While one should avoid heat, humidity, and direct light, it is not necessary to refrigerate grape seed oil. Properly stored, grape seed oil can last for at least one year with minimal deterioration.
The majority of fatty acids in grape seed oil are of the omega-6 family, represented by the high linoleic acid content which comprises about 68% of the fatty acid content in grape seed oil. The other fatty acids are largely of the omega-9 family (oleic - 19 %) with small amounts of saturated fatty acids (palmitic - 7.2% and stearic - 4.8%). Grape seed oil also contains small amounts of the beneficial omega-3s.
Grape seed oil is a culinary (cooking) oil and is not to be confused with grape seed capsules that are comprised of powders extracted from the water soluble components of grape seeds. Grape seed oil is rich in linoleic acid (omega-6) and is reputed to contain higher amounts of this omega-6 fatty acid than any other oil or food source. Grape seed oil is also a particularly rich source of antioxidants, vitamin E, and other phytochemicals.