Usually, this is true. But LiteOn drives are special and are very hard to really kill; it takes a bit of effort to actually kill them.
I did the speed test you mentioned and my read speed is only 3-8x (quoted in specs as 16x max). Is this normal for this drive?
Yes. You have to look at the fine print. The specs say 16x, but that is only for commercially-pressed single-layer DVDs.
And, if I use your Omnipatcher to fix the speed, as you mentioned, I want to make sure I do that right.
Don't be afraid of OmniPatcher; we took great lengths to make it fool-proof. It won't let you do anything that you shouldn't be doing.
but how do I know which file to choose? There are several files listed for my drive, and no descriptions to differentiate between them and what they do. If all I want to do is up the read speed, I want to make sure I don't apply some other firmware that totally changes the drive.
Well, most of the firmwares listed on our site are stock (original/unmodified) firmwares. The only difference between them is the version and whatever LiteOn changed between their various versions. Generally, newer is better. Since you are going to be using OmniPatcher, you should just ignore whatever patched firmwares that we have, as that will help clarify things. (All patched firmwares on our site are patched by OmniPatcher, and are really intended for people too lazy to download OmniPatcher.)
In your case, you should either use whatever your current 1633S firmware is (if you are afraid of change and only want fast read but don't want anything else) or the latest 1633S firmware (BS0S) or the latest 1653S firmware (CS0P, but this will require that tick OmniPatcher's "cross-flashing" patch). It's really just your personal preference which of those three you want.