I've got a 95, 06, and 14 chevy vehicles, none throw the cel when it's time for a regular oil change. The Cobalt and Malibu have little messages that pop up.

Yea, mine was on the verge of being empty, I think that's why it threw a code. No oil pressure...

I have been following this unfold and I am at a loss for words! Truck is running better than it has in months since those codes popped up is just plain weird...

Well I changed the 02 sensor and the truck is running great. Had the codes cleared and the one for miss fire returned right away. NOW it gets stranger. After a week of being on and flashing all the time it has some how cleared and and no codes show up when checked and I did NOTHING to fix the misfire!!!!!!!!!!! I think the system is messed up!!!!!!!!!!!!!!

So, lemme get this straight.

First, your truck had a cel, with the code being a mysterious oil change code?

Then, that disappeared, and O2 sensor codes popped up, while you also had a flashing check engine light, but the truck somehow running great?

You change the O2, clear codes, truck is running great still, but now misfire code is present?

And after a week of this, the misfire code disappears?

What all have you checked? Do you have access to a code reader, or are you having the parts store do it? If you have one that shows live data, post up the fuel trims.

Also, check your fuel pressure and leak down, and post up the results

I'm interested in seeing what the final answer is to this. My CEL comes on and shows the misfire code also. It can go away at random times and then return. I took it into the local dealer and the light was off again. They said they couldn't read any codes and the engine was running smooth.

A worn dist can have enough movement that at mid to higher RPMS it can move internally enough to show a miss fire.
Upon returning to a idle depending just how the internals settle back it can either stay at miss fire or settle to a point that it fires right...
Usually the lower gear has partial worn teeth and has lets say the lower half of the teeth are worn and do not make 100% contact .
The very top of the gear and shaft bushings are worn enough that at mid and higher RPMS the shaft walks up into the slack causing the miss fire ....
Also check the magnetic pickup wheel on the shaft for cracks - crack opens up it throws a double signal and it miss fires , crack closes up it don't

No I do not have a reader but I did just order one. The last time I had the codes run I went to 3 different places and they all said the same thing about the miss fire. I cleared the codes after changing the 02 sensor to see what was left. I had NO CODES and it lasted that way for 6 days then the codes for the 02 sensor and the miss fire came back. But no flashing light until today. I recently had a ENTIRE new dist installed and the plugs and wires are less than 2 years old (maybe too old now) and I know nothing about the stock coil. I looked at everything and the only ODD thing I found is the shop that put in the dist used a couple of wire ties on the ends of 3 wires like they would NOT stay in the cap. They all feel tight and AGAIN the truck runs GREAT!! The only problem I have found myself (which really is another issue) is when I looked at my fuse box the female end that the fuse plugs into for my window washer has fallen down inside the fuse box!! I am about to give up on this blazer and here I set with new upper control arms ready to go on,just waiting for the shocks that I ordered!!

SMILE owning a Blazer is a love hate relationship - Tossup on witch is first ....