I have a 83 300SD Turbo Diesel. The owner’s manual recommends using diesel 1. The problem is that we do not have D1 here in NYC but we do have D2. Just recently, a gas station in my area started to sell D2 with an octane of 50. I’ve been using D2 with octane of 40. The answer seems obvious and the tendency might be to use the higher octane. The problem is that the gas nozzle on the higher octane diesel does not fit well in the car. My question is why? Is it because I should not be using the high octane diesel?