OFFLINE

their 2 different things you can use for your marker one oil one is lube.
oil
some low end markers use oil and sometimes can  use lube.
oil you can use is 3 in one oil it works great in low end markers only need a drop or 2 on orings to prevent them from cracking or breaking.
the bad thing about oil is that it dont stay in one spot and spreads everywhere in your marker dont put oil in the barrel it makes it very unaccurate.

lube
lube is for alot of high end markers like the invert mini cuz they have alot of orings in it and moving parts so you want the lube to stay in one spot. their is alot of different kind of lube all of it is different and can be better in some markers. lube rubs on to your orings and it sticks on them and dont spread around everywhere in the marker making it less to lube all the time. TechT Makes good lube it most liked by players.

Markers that can use both are Tippmann markers B.T. J.T.

OFFLINE

Well, i can add a little info onto what you've already got going on. I know for example, since I own a shocker, they recommend grease for the bolts because they are not smooth, and oil would not lubricate properly, however, if you had the bolt polished, oil is useable. So generally speaking, grease is in most cases a superior lubricant due to its different properties with majority of the markers out there due to most markers having a non mirror polished finish on their bolts. I use dow33 on my phantom, and my piranha, where as they say to use oil, and my consistency is usually really great all throughout the day due to the fact that the grease doesn't shoot out of the marker and continues to lubricate thus reducing wear tremendously.

Dow 33 is an all purpose grease while dow 55 will swell your orings and should only be used in certain scenarios where there are loose tolerances around the orings. There are many types of grease out there (which are all usually dow33 or 55 based), but in general when it comes to oil, its no different from one bottle to the next. Usually you can bu a cheap bottle of pneumatic tool oil and be set cause its the same exact thing.

The grease I recommend is dow33 and more specifically a product called lurker lube. It comes with great reviews, is really cheap compared to other greases, and has bits of teflon impregnated into it to reduce friction.