zlacker

I've also wondered about whether to fully fill my tank or drive on a small amount so that I'm not using fuel to carry fuel. Do you know of any metrics on that?

>>oniony+(OP)
you can probably work it out but you have to make a lot of assumptions :)

Ultimately how much is your time worth? in the example given drcongo's time is worth £1.28 an hour.

>>oniony+(OP)
I haven't made any calculations, and it's more a hunch, but considering you usually need to remove hundreds of KG in order to make an impact on how much fuel is being spent, 40-50L of gas (~40KG difference between full and empty maybe?) would have an marginal effect on how much fuel is spent to carry a full tank vs 10% filled tank.

Besides, with a smaller tank, you'll make more trips to tank it, and also have less choice to go to gas stations that are further away but have cheaper price. Then again it becomes a question of "Do I want more time or more money?", back to square one :)

Edit: Also, someone correct me if I'm wrong, but doesn't the fuel pump use fuel itself as a coolant or something? Never investigated myself, but some car-knower once told me that running the tank on low always isn't good for the fuel pump, or something like that. If that's true, running with 10% of the fuel would mean more maintenance too, potentially removing any savings in the first place.

>>embedd+R
> doesn't the fuel pump use fuel itself as a coolant or something

I know very little about these things, but my understanding was always that any form of liquid pump uses the liquid itself as coolant to some extent.

>>alias_+u2
Yeah, fair enough, I think what he mentioned though, wasn't just about fuel going through the pump being used as coolant, but some extra process that only happens when you're not running below say 10% or whatever, an extra cooling process that only runs when you're not low on fuel. Maybe I misunderstood him though and it's just about the liquid passing through.

>>oniony+(OP)
Unless you're driving a lorry with a 120L tank, it's negligible. We're talking like, 100 mL per 100km.

>>embedd+G4
I think the fuel passing through is the only method that could be used to cool, the volume of fuel required is presumably constant, regardless of how much fuel you have left, so the amount passing through the pump should be the same until you run out.

On a related note, my car has a fuel heater, to pre-heat the Diesel before it hits the engine, I assume this is typical in modern cars, but using the fuel as a coolant would presumably contribute positively to this desire for warmer fuel entering the cylinders.

>>embedd+R
> Never investigated myself, but some car-knower once told me that running the tank on low always isn't good for the fuel pump, or something like that.

The main issue is that it risks pulling detritus from the very bottom of the fuel tank, usually a bigger issue in diesels and I suspect less of a problem these days.

>>janspe+Cu1
Aah, I have a diesel car, maybe that was what he was alluding to! Car is from 2017 so not that old. Thanks :)