Similar to the stinky gas thread. I ran my truck out of old gas mixed with new gas but it left a thick sticky varnish inside intake runners. I know cause I took carb off cause it was acting funny probably from the old gas. What do you recommend running through the tank to maybe clean this thing back out? Interested in additives only right now as its a cheap slant 6. Thanks!

People are going to suggest seafoam, however my experience has been the mechanic in a can products don't work and that you would be better off just running it with fresh gas and it will slowly dissolve the varnish.

Have you looked at the plugs?
If it was bad enough to varnish the intake,
it might have mucked up them as well.
I agree with the above post.
I just think the plugs might be the reason it's running poor.

Yeah Ive changed the plugs not to long ago so Im staying on top of them. Intake, exhaust all feel sticky. Im going to re- clean the carb out as i feel its getting gummed up to. Truck runs surprisingly well otherwise. Ill keep wth the new gas.

Glad you're keeping on top of things.
Old trucks like attention, and give back good service.

I just meant since you put the old gas in it.
I figured it will gunk up the plugs if it's gumming up the intake.

I'd still use that old gas myself, just cut it a lot more with new.
By all means don't do it if your uncomfortable with it.
Happy motoring.

Oh Im committed now to using it. Just trying to get past this stage.

Try WD-40? It's surprising stuff sometimes...There used to be a product called Mix-e-go that was unbelievable! It would remove the carbon from the entire exhaust all the way to the tip and make you lower your idle speed.

It is hard to know how "gunked up" it is or if it matters. Personally I would just run it if the gunk is not super thick... or pull it off and physically clean it. As long as gunk stays put, I do not think a coat of varnish will have much impact on how the engine runs or lives.

This is one of those things that starts with best intentions. I ran the tank out of varnished gas and the carb is full of mud type sludge, again. Filter failed. Thought it was a one time thing but Im going to pull the tank anyway. Ill try and pump it out tomorrow. The varnish film doesnt seem so bad now. Oh well

Startron products makes a fuel system cleaner that will take care of it. It will also clean the varnish from your tank so you will need to change your fuel filter as you will be amazed how much stuff comes off your tank walls.

Seafoam is the bomb for cleaning minor deposits. Use it for gummed up carbs on cars & bikes. At least 50% time I avoid having to pull the carb. Now if you run Startron you won't have these issues in the first place. I can leave a bike, mower, etc for 6 months with startron in gas & it'll fire right up like it was yesterday.