First time posting, have no car knowledge. We filled my wife's 2017 Dodge Durango up at a new gas station, shortly after that we noticed sluggish acceleration and trouble going off stops. We took it to a jiffy lube, got the oil changed (it needed it anyway) and had them do a fuel system cleaning.

We also picked up some octane booster.

This morning when we started it, black smoke came out and then thin white smoke. I have it idling to burn off the bad gas (guessing). While idling there is no white smoke, when I rev it every 15-20min thin white smoke comes out and then goes away. I've kept an eye on the engine coolant and it hasn't dropped any. There are black flakes on the driveway where the exhaust is.

I read several horror stories that it could be a blown gasket or something. Should I be worried or is it just the car burning through the bad gas and other things we put in it?

  • Welcome to Motor Vehicle Maintenance & Repair! May 5, 2019 at 18:19

2 Answers 2


Update: Turns out the Circle K put diesel in their unleaded tank. So hundreds of people filled their cars up with diesel. Getting our vehicle towed to local dealership and contacted insurance company.


More than likely this is just residuals from the fuel system cleaning. Usually, to do cleaning, they'll put chemicals in the intake tract to ensure the upper valve train is cleaned out. I don't know if your Durango is direct injected (DI), but it very well could be. In DI engines, there is a propensity for carbon (or really gunk) buildup on the back of the intake valves. In port fuel injected vehicles, the injector sprays fuel on or near the back of them which keeps them clean. In order to clean them in DI engines, you have to inject some kind of chemical cleaner. I'd suspect this is what Jiffy Lube did and you are just seeing a little bit of residual from it. I'd also suspect your suspicion is correct ... you got bad gas from this "new" fuel station. Needless to say ... don't go back there.

  • Whew, thank you! I planned on getting the Durango to half and filling it again with 91 octane. Should I do another octane booster? There was knocking yesterday when acclerating, but that seems to be gone now when I rev to higher RPMs.
    – Zlyback
    May 5, 2019 at 18:28

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