Fuel additive survey. Is it “Snake Oil”?

[CAG]

Originally Posted by craigav

I use "Sta-Bil" in my gas but only the last tank full of any RVing as sometimes I don't get out as often as I used to and prefer to keep the gasoline as fresh as possible to keep it from separating or gumming up (I also always run the engine at least monthly). I also use Sta-Bil in my portable generators and lawnmowers but again, only when I am not using them (storage). ~CA

Sta-Bil or SeaFoam which I prefer, is great but it needs to be run through the system or your carb and other areas varnish up. In other words if you put it in your tank and park it for the winter, the varnish remover is only in the tank. That does nothing for the carb and the gas in the bowl and carb turn to varnish and the engine will not start or runs poorly when you start it up again.



Put the Sta-bil/SeaFoam in the tank just before your last use for the season or you park it for a prolonged period. Do you lawn mowing, or whatever. You can either fill or not fill the tank before parking but if you fill the tank add the required amount again.



With RC engines and some small engines the norm is to run them dry before you put it up for storage.

[CAG]

Originally Posted by Jagiven

What works for diesel is not relevant to the OPs question for a Class C MH.

Read the directions of what ever it is you are adding many work in any engine. SeaFoam for instance says gas or diesel

[craigav]

I agree with you CAG and suggest the same for everyone. The way I try to do it is add the Sta-Bil in with the last tank full fillup as that way it gets mixed well and into the fuel lines as I drive to my home storage area and I also run the generator to get it in there as well.

I have some gas engines for different things and I have had better results keeping the fuel tanks full for storage with Sta-Bil (I also use Sea-Foam but not together, one or the other). On some equipment that I have I have found that an empty gas tank has a higher likelihood (in my experience) of tank rusting issues than with a full tank of gas that is treated, not too mention I like to start the engines monthly. For a non-rv point, if your small engines do not have a fuel shut-off I would highly suggest to add one, then run the engine prior to storage with the fuel shut off until the engine dies, since doing that I have had very few carb issues as CAG mentioned that the gas will sooner or later evaporate out of the carb (regardless of what treatment you use) and what doesn't evaporate is the gum and varnish and if you have enough of gum and varnish in the carb then you would likely save yourself a lot of frustration by simply replacing the carb (or clean it if you know how but a cheap lawnmower carb doesn't cost much).

Also as a thought, if I didn't have the time to run any of the engines monthly, I would agree that running entire tank, lines, and carb completely empty would be best and then visually check that the tank is completely empty as even a small amount of fuel (except perhaps non-ethanol) left in the tank will collect moisture and may rust your fuel tank out as I have experienced before.
~CA

[craigav]

I wanted to add a real world tip that I suggest may be even more important than any additive while on the road RVing. Back about ~15 years ago with my 5er and Duramax I re-fueled at a small out of the way station and got about 10 miles before the engine starting running poorly, fortunately I had another fuel filter to try and sure enough the engine ran better again for about another 10 miles which placed me in a small town where I purchased 3 more filters and ended up using every one of them before things settled down.

Point being and this is for all fuel types, I got so concerned at that time that almost every fuel up since then and in particular when refueling at smaller gas stations, prior to pumping a tank full of bad fuel I started using my quart size ratio marked container (commonly used for 2 stroke engines to mix the gas and oil but works well for additives as well) to pump maybe 10 cents of fuel into the container and then visually inspect the fuel, if it looks good then I pour it in the tank and fuel the tank. While over the many years I have found perhaps 3 or 4 times dirty looking fuel (some stained and some with small particles), in one example I stopped the pump when I saw this and tried the same test again with the mid-grade fuel which was much cleaner looking, not sure what was going on in the fuel station's fuel tanks.

In summary, it is best not to ever get crap fuel in the fuel tank, if you do then Sea-Foam can likely help but depending on the crap percentage and content then maybe not. I will add though that I have never found crap fuel at high volume off the interstate truck stops or gas stations so I don't always test as I probably should at those stations, but I always check with this method at smaller more rural fuel stations, especially those that I don't see others purchasing fuel before me... oh, last tip, carry a spare fuel filter and the tools needed to change it. ~CA

[CAG]

Yes a common post/warning on most diesel forums. Buy your fuel from a location that pumps a large volume of fuel or run the risk of fouled filters and lines. I would not bother with inspecting fuel unless you bought from a location that it is pretty obvious they don't pump much fuel. Costco, Sams, and most of the truck locations on the Interstates are pretty safe.



While no amount of high pressure will force fuel through a clogged filter it is more likely that if you run a lift pump the filter will clear enough to run for awhile but a new filter is the only way to get moving again.