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BigChiefS4 t1_ixtlxd7 wrote

Reply to comment by [deleted] in ELI5: Why do you have to turn your car off when you fill up your tank? by logan0921

Your engine oil will not freeze. WTF are you talking about? I live in MN. In northern MN it regularly gets well below zero. Last winter it was below -40F and my Q5 TDI started right up after sitting outside overnight. If the oil was frozen ( which it won’t), the engine wouldn’t even be able to turn over.

Even if it COULD freeze, it isn’t going to in the 5-10 minutes it takes to fill up your gas tank.

So much misinformation in the thread…

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kyrsjo t1_ixu2h7p wrote

Yeah, a huge lump of iron sitting inside a somewhat isolated bay won't go from pretty warm to -40 in a few minutes. That said, starting a really cold diesel isn't fun, and probably puts a ton of wear on it. Fuel freezing isn't really a problem tough, since there is a different fuel blend in the winter...

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BigChiefS4 t1_ixuq4lj wrote

Yeah, my Q5 TDI was not happy to have to start in -40F temps, but it did start. I let it idle for a good half hour, just to get the fluids going. The thing with diesels in the winter is that they are more efficient engines and don't run as hot as gas engines, so they take forever to warm up.

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After letting it sit idling for a half hour, I drove the 10 miles into town (we were staying in a primitive cabin in the middle of the woods) and by the time I got into town, my temp gauge had just started to move up. When I pulled into the gas station, it went right back down to zero. On the drive back, it barely moved.

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