Does the car run ok? I think if you had that much water in it it wouldn't run. The percentage of whatever it is in there will be the same as in the tank, I think, so if it is 15% in the jar probably it is 15% in the tank. 15% in the tank would kill the motor and it would not run if it were water.

It looks like old heating oil to me. And if that's what it is no worries, just drive it.

Tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.