H2NO

I finally bought a bottle of Techron to treat my car to a little cleaning before its final oil change and possible hibernation (depending on weather). I have 3/4 in my gas tank. If I pour in the Techron now will it reach its intended potential or should I wait until the tank is near empty?

dcdude

Actually, in other cars I wait 'till the gas tank is 1/2 full, pour in the FI cleaner, then top off with more gas so it "mixes" as much as possible.

I'm not sure if there's more benefit having the higher concentration of cleaner that you indicate.

2Many Cars

Too much Techron can actually be a bad thing. I'd do what Chuck suggests and then try to run the tank down and refill with fresh gas (and maybe some stabilizer) before storage.

Kika

My mechanic told me that these cars actually have a pump that circulates the gas, thus the standard of putting additive in, then filling with gas, to mix is not necessary.

Can anyone confirm?

Stealth 993

90% of all cars have this, it's called a "return system" Only the newer direct injection, & other cars like that have a "return less system"

2ndof2

Just curious - does the recirculation system in the fuel tank do anything to help filter out and prevent contaminants/sediment building up in the tank over time?

MDamen

No real help with the filtering. The pump puts out more flow than the engine can use. The fuel pressure regulator on the engine keeps the pressure at the right spot by returning the extra fuel to the tank. It probably returns into the top of the tank somewhere. The filter is after the pump but before the injectors, so it sends clean fuel to the injectors. I don't think you would see any difference in the stuff in the bottom of the tank.

andrew911

Funny we all do different things. I put the full techron bottle/amount needed in at the gas station when the tank is near empty, then fill up. Then I don't refill until the tank is near empty again to get maximum flow of techron additive through the system (i.e. drive the whole tank, few hundred miles, with the proper mix of gas and techron). I don't do this before storing, actually I do it after storage in the spring or summer to free up any gunk that may have formed. I have in the past couple of years been putting some Stabil (the pink stuff) in with a full fresh fill up of gas before winter hibernation.

By the way, before putting the Stabil in I never had a problem with gas going bad during winter storage, and in 20 years of 911 ownership (3.0, 3.2 and now 3.6 liter), I've never noticed any difference after using techron. Heard it was the best stuff, and have been using it every year or two just to keep things clean (car gets driven about 2K miles / year), but if you really must know my feeling is these things aren't necessary for cars that are going to sit for 3-4 months/year- the gas today has pretty good additives already. I'll keep using them though becuase I'm **** with my cars

mstolo

I just feel sorry for you poor guys having to put the car away for the winter. I'm just disappointed that I have to keep the top up...most of the time.

csertich

I do the same thing as Andrew911. Wait till tank is almost empty and pour techron in before filling up. Then I try to run that tank dry. Once I put the techron in and fill up, I feel obligated to drive the car like I stole it so as to 'push' the techron through the fuel system at high speeds thinking that it will clean it better.
I just fool myself that this is doing good while having a hell of a drive.
My wife rode with me after my first bottle of Techron. Now whenever we go out for a drive, she asks 'this isn't gonna be a techron run, right'?
chuck

Steve Weiner-Rennsport Systems

IMHO, Andrew911 & Chuck are doing it right,...

One sees the most benefit from any fuel treatment by putting the additive into a near empty tank, filling it up to mix it well, and then driving it "in anger" for an hour or two to clean up the soft carbon buildups on the back of the intake valves and injector pintles.

I've really had excellent luck by following the same procedures for many years using both Techron and LubroMoly products. I can always feel the difference in throttle response.

ZombiePorsche44

Here in CA the Chevron 91 oct has techron in it so I am always keeping carbon deposits down but still run a full bottle in the method described once a year for good measure.

ZP44