Stormin Mormon wrote:

The mileage on my replacement Blazer is a bit low.
15 MPG, where the last Blazer ran about 18 MPG.

A friend reccomended Berryman's B-12 gas additive.
Says it's $2.97 at Walmart. Found it at Walmart. top
shelf, and this store had only two left, so it took a
while to find it. A couple days ago, I put in one can
of that B-12 fluid. I'd checked my mileage at 15.2 on
the last tank. This next fill up came up 16.3 MPG. I
don't think I changed my driving style, and the weather
is much the same. So, I'm figure that fluid did some
good.

It's pretty decent stuff, I use it in higher concentrations than
specified when fueling my mower and other yard equipment in the spring
after they sit unused in the winter (I also use Sta-Bil in all fuel). It
does seem to help clear out any gunk that was forming. For automotive
use, you really have to use it on a nearly empty tank to make sure you
get a decent concentration to the engine.

Assuming this is a fuel injected engine, I prefer to use one of the
pressure feed injector cleaner rigs that feeds the injectors directly
via the fuel rail test port. These units run (at idle) the engine on
100% cleaner and work very well. The cleaner rig runs $100-$200, but the
cans of pressurized cleaner are only ~$6-$8. You will see a very
noticeable improvement after use if the injectors were gunked up.