There are several things you should avoid storing in a self-storage unit that are typically self-explanatory. Food is one example, since it can draw rodents and other pests, thereby causing an infestation in the building. That would not make you a very popular tenant with the landlord OR the other storage unit renters. In addition to these "do not store" items, there are several items that stain the cement floors of storage units. There are some accompanying reasons why you should not store any of the following three items.
If your car has ever leaked oil on your garage floor, then you have seen the staining results of automotive oil. Even in its own bottles, it can eventually leak, and a few drops of the stuff on the cement floor of your storage unit will spread out and soak in. Almost nothing can remove it, and then you might be out of your security deposit.
While you might think that cooking oil would be safer to store than automotive oil, it actually is not. Cooking oil is often made from corn, safflower, natural vegetable oils, and other safe-to-consume food products. That means you are drawing pests in by the hordes with the smells of the hot oil in its containers, and the minute a bug or rodent chews through the corner of the plastic bottle, you end up with pools of the cooking oil everywhere. It becomes a pest smorgasbord that stains, rots, and leaves behind more than just greasy residue. Bottled and boxed does not prevent any issues, so you should chalk this up under "food" and not store it in your unit at all.
Wood Lacquer or Stain
By its very definition and name, wood stains and wood lacquers are meant to stain and stick to whatever they are applied to or poured on. Pests will leave these alone, but if these are accidentally tipped over or dumped, they are a nightmare to clean up. Nothing but furniture stripper will pick this stuff up either, but you cannot use that until you ask your landlord for permission to clean up the mess using a stripper. By then, your proverbial goose is already cooked, and there is a chance that the stripper would have a very bad side effect on the cement, making it chip and flake. Ergo, do not store this stuff, and do not store paint stripper or thinners either.
For more information, contact local professionals like Colfax West Self Storage.