I noticed this one months ago.

When we get to the College of mages (or whatever it is called) we can make our own spells.

If I have a spell that allows me to carry an extra hundred-weight of stuff, for 120 seconds (two minutes) and I cast it twice in a row - all it does is replace the first instance of the spell that I cast.

I tried something new though, and this is interesting!

If the spell has a different NAME but is OTHERWISE IDENTICAL they stack!!!

(!)

~ I'm not kidding, try it and see.

Make a spell of FEATHER. Make it the maximum, 100 units, plus 120 seconds. Name it "FEATHER 1" (or whatever you prefer)

Make the EXACT SAME SPELL, but name it "FEATHER 2"...

FEATHER 3...

FEATHER 4...

(You get the idea)

As you cast them one behind the other the amount you can carry goes up by 100 units with each one BECAUSE THE DIFFERENT NAME MAKES IT A DIFFERENT SPELL...

The game treats it as something else

I've fast travelled overencumbered by more than 1,000 pounds (or however you think of it) many times.

Have fun with that!

~Wolfie

I do sort of the same thing with acrobatics - that is one of the few skills where the benefits keep accruing beyond 100. Two spells to fortify acro for 100 for about 15 seconds with different names. The first one boosts Buffy's 100 acro to 200, and the second one boosts it to 300. That's plenty enough skill and time to let her get up to about any safe shooting perch she wants.

Although the tip has been known for quite some by those who have played Oblivion a long time, it is neat that you 'discovered' this via experimentation. And it's always nice to share tips because new folks are starting Oblivion all the time.