Help Diesel Gas Mix

[coasterguy]

Well, I didn't know what forum this belonged in so here goes. A family member just topped of the gas tank with diesel fuel

(vehicle is 99 passat 1.8t) Probably about a quarter tank. It still runs but will it be okay? I'm not really worried about the engine but rather things like the O2 sensors and Catalyst.

Thoughts / suggestions please...

 

[Quattro Pete]

Don't run it. Drain the tank.

 

[pitzel]

Diesel shouldn't/won't have any negative effects on the O2 sensor and the cats, but the octane rating of the fuel will be very low. The knock sensor might be retarding the timing due to the low octane content of the fuel.

I would suggest that you fill it up with premium every chance you get for the next little while. To dilute the low-octane fuel that is in the tank.

A quarter-tank of diesel would be just like running something like Marvel Mystery Oil, or a couple quarts of 2-stroke mixture in a car. Not the end of the world, but definitely not great for performance or emmissions in the long run.

 

[Hirev]

Well I would be worried.

Years ago a neighbor put about 3/4 of a tank of diesel in a gas powered van by mistake on a trip. It blew up within 30 miles. I mean there was holes in the block blew up! Drain it all out.

 

[Master ACiD]

as already stated, diesel has a very low octane value. somthing around 30-40 iirc, if the tank isnt going to be drained, avoid any sort of load while runing and use the throttle as spraingly as possible. avoid boost _AT_ALL_COSTS.

diesel will make the engine run lean, so the computer will correct this by adding extra fuel to richen it back up to scoich. computers have this ability built in because oxygenated gas a similar effect on the afr, although less of an effect than diesel.

just be real easy on that throttle, and fil with 93 or higher asap as already stated.


how did this person manage to get diesel in there in the first place? the diesel nozzle shouldnt even fit? are they sure they filled with diesel? you should be able to tell by the nice diesel exhaust smell.


does this car have a knock sensor, that should help a bunch.

 

[Quattro Pete]

A coworker filled up the company sentra with diesel. When he drove off and soon after the car died, he just called the office to arrange for help because his car "stopped working for no reason."

Not sure what was done to the car apart from just draining the tank. Later on, I ended up driving that car. I don't know if it was related, but within a year of that incident the cat failed and had to be replaced.

 

[coasterguy]

Well I found that the octane of diesel is only about 20! so I think it's siphon as much as possible out and refill with the highest octane available in the area and maybe a shot of octane booster for good measure.

Thanks everyone.

 

[Willy_G]

How did the diesel nozzle fit the gas filler?

 

[Quattro Pete]

Willy, that's what I'd like to know, since from what I've read, the diesel nozzle is thicker. Unfortunately, that coworker no longer works here, so I can't ask him. Coasterguy?

 

[coasterguy]

Yes it's bigger and doesn't fit. An elderly member of the family was coming home at night after a stressful day and thought it odd that they had to hold the nozzle up against the filler and that there was considerable splashback. After several gallons it registered that it was a Diesel nozzle......

 

[Shaman]

Pump as much as possible out. If you don't drain the tank, put in some High octane with some Xylene or Toluene, of even find a race gas station if you are really worried.

My dad put a gallon of diesel in a 65 mustang, and soon after fouled the plugs.

 

[DJ]

Older engines I could definetely see damage from detonation, newer stuff though with know sensors I think will pull sufficient timing to avoid damage so long as you stay out of the throttle. The Race gas idea is a good one just make sure it is UNLEADED. some race fuels are still leaded and lead would kill the cats and O2s, I don't know what the diesel would do.

 

[k1xv]

As a diesel vehicle owner, I can tell you that diesel is available through both large, high flow rate nozzles, and small, standard flow rate (gasoline size) nozzles. The large ones are usually at the "big truck" island, and the small ones are on the island along with the gasoline pumps.

Some diesel vehicles will not readily accept the large nozzle. My GMC Duramax pick-up prefers the smaller nozzle.

 

[michaelc80]

Years ago when I was in the transportation business a new driver filled a diesel truck with gasoline. It made it about a mile down the road before it died.