On our recent road trip to Durham for a Tech-Recipes Summit, we accidently put 4 gallons of diesel in our non-diesel vehicle. Googling the obvious keywords didn’t get us very far, so I thought I’d share our experience in the hopes it would help others. We ended up with no problems, but I’ll just warn you that this information is from a few sources, contains suggestions based on a few experiences, your milage (heh) can and will probably vary. If in doubt, please seek professional help. I’m only writing this in the hopes it can help some folks — I know more about Ghz than MPG, so take the contents of this post with caution. There are many different cars and engines and I bet that their reactions to diesel contamination will be very different. You are responsible for your vehicle and the decision you ultimately make is your own. I recommend towing your car to a mechanic if you have any hesitation. Enough gluteal coverage? Let’s continue.
If you face this situation, your solution will be heavily influenceded by a number of factors. I will describe our condition in detail and that of a friend who also had a similiar problem but with a very different outcome. Our 20 gallon tank was mostly empty (it still had 2-3 gallons of normal gas) and 4 gallons of diesel were added. We did not start the engine at this point, but instead used our phone lifelines.
We called a friend back at a home who completely filled his tank with diesel.. while the car was still running, pretty much the worst case scenario. It stopped running and would no longer start. The only solution at that point was a tow to a mechanic and the removal of the engine and fuel tank and most of the rest of the fuel handling system. Each component had to be cleaned to get the diesel out. My heart sank at the thought of this.
David knew an excellent mechanic and was able to reach him by phone. Given our situation, he told us that if it was his car, he’d fill it up with the highest octane fuel, use gas treatment and fuel injection system cleaner, and drive the diesel out of the system. He warned that the car would not like it, the engine would knock and stutter and generally not want to cooperate. After a few tanks of good gas and gas treatment and engine cleaner, he recommended replacing the fuel filter. If this solution worked, it would be the cheapest.
The only other alternative was towing the car to a mechanic to have the fuel tank drained and possibly cleaned. This was possible because none of the diesel had been pulled toward the engine as a result of starting the engine.
After much contemplation at the gas station, I concluded that there were three potential outcomes:
- Fill the car with good fuel and treatments, say a little prayer and drive the diesel out. It works and the expense is $50 in extra gas cost and fuel treatments.
- Follow the steps in option 1, but with too much diesel in the tank, the engine becomes inoperable. If the good gas/fuel treat plan doesn’t work, expect $2000-3000 in repairs.
- Tow the car immediately to a mechanic and pay $500-1000 in repairs to guarantee no damage to your car.
Option 3 is the safest by far. We opted for #1 and it worked out well in our case. We had 4 gallons of diesel in a 20 gallon tank, a 20% ratio of diesel to gas and about 14 of the 16 gallons of gas were high octane.
If we had topped off the tank with diesel, option 3 would have been our only possibility. Diesel will not run a gas engine. Diesel != gas. With 20% diesel in our tank, it was, as David’s mechanic friend said, like getting a tank full of really bad gas. There are fuel filtration measures in place to protect the engine from some bad fuel, so we lucked out with the ratio we had. 100% diesel certainly will not work. If you have a ratio somewhere between, you have a difficult decision to make. My advice is to consider it carefully and take the safe approach and have your vehicle’s stomach pumped, especially if you are not a gambler at heart and certainly if you have a ratio much higher than 20%. At 20%, our vehicle was reluctant to start and did knock some. It also stopped a few times while driving. David suggested topping off the tank after a few gallons were burned and when we did this, the engine behaved much better.
After returning a thousand miles home and driving around here for a week, we took the vehicle to a dealership for an oil change and asked for their advice regarding the fuel filter. They suggested that if the car was behaving properly not to worry about the fuel filter as this is not a quick replacement.
Long story short, if you are in this situation, take a deep breath and stay calm. If the diesel isn’t in your engine yet, there are solutions. Even if you drive off with diesel, your car can be repaired.