Lots.
They are simply built much tougher. Diesel engine have a compression ratio that is much higher than any petrol engine. As such the internal parts must be built stronger to handle the higher compression. Also the diesel fuel itself provides some lubrication. These factors provide for a much longer life.
There's a lot of variables to that question. For instance, how big of a tractor? Is it gas or diesel? And, what is it doing? Plowing would use considerably more fuel than cutting hay, for instance.
Depends on the milage but usually around 28-50 thousand Depends on the milage but usually around 28-50 thousand
Depends on the car and the milage and the seller
That would depend on it milage and condition.
In general unleaded in diesel is worse but it depends on how much unleaded went into how much diesel.
Depends on the milage the car gets.
Need milage of vehicle in question to answer
how much gas milage do i get with a 2005 chevy cavalier?
It depends on your car's gas-milage.
It depends on what kind of milage you get.
How much was diesel at the pump in 1991