Is this good for a 2003 Chevy Blazer?

As long as your blazer requires dot 3 brake fluid it should work fine. I used it in a 2011 f150.

is this a synthetic brake fluid? i need original non synthetic dot iii brake fluid and can't seem to find it.

Kindly note that you can find the original one, it's distributed nationally through the largest retail, discount, auto, and convenience store chains. And it's Clean all dirt from around cover on master cylinder before removing. Fill unit to level specified by manufacturer. Replace cover. Check fluid level once a month.

Can I use this in my 1991 Cadillac Brougham?

I don't know for certain, but check the DOT specification recommended in your owner's manual. The DOT specification also may be indicated somewhere on the reservoir cover

ASIN	B000FW7VU0
Brand	STP
Customer Reviews	4.7 4.7 out of 5 stars (383)
Date First Available	5 February 2013
Item Weight	354 g
Item model number	18669
Manufacturer	STP
Manufacturer Part Number	17924
Model	Protects brake system
Product Dimensions	7.62 x 7.62 x 15.24 cm; 354.37 g

STP 17924 Heavy Duty DOT 3 Brake Fluid, 12oz (354 ml)

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