Civic EG

i have a slight head gasket leak no oil or water mixing but compression gets into the coolant well its gotten a tad qorse lately im not running a thermostat cause if i do it overheats so even without on now it warms up quick and almost runs normal oper. temp. even though its the dead of winter will that cause decreased mpg?

Yes def. If you don't have good compression. Your engine is not running at the rate it should which will cause worse mpg Make sure you get the head resurfaced when you do the headgasket

^ what he said..

theres alot that plays a role in MPG.. stuff we cant control and stuff we can
but the stuff we can.. make sure is up to par.. like tires aired up and healthy motor and shit like that

kinda what i figured i am planning on having the head resurfaced im fixing to do the headgasket among many other things i have to get done to it itll be down for 2 weeks probably i just noticed recently my MPG sucks and it happened at the same time my problem got worse with the gasket

if youve got "compression" in your coolant, you've got more issues than you think.

fix it now, before it leaves you stranded.

in short. you have a blown headgasket, and yes this will drastically affect your fuel mileage.