I use a 14" Smart Parts Tear Drop on my Tippmann model 98. I just recently added a custom made drop forward.
Cheap, does its job
A little thin
I've been using this because it's cheap and it does its job...it is a bit thin but it keeps the bolt and o-rings lubed so their is no wear and tear on them. I would recommend this if you don't want to spend a lot of money and need marker oil. But if you don't mind I would spend a little more money and get better quality marker oil.
But if if you need a marker oil for cheap...if not buy something better quality.