Why do some types of oil combust easily while some take some effort to catch fire?

e.g. gasoline vs engine lubricant? 

Thanks in advance! 
The size and surface area of a fuel can determine how quickly it will catch fire and burn [1]. For example, a twig catches fire easily because it heats up easily and has a large surface area [1]. The amount of oxygen available will also affect the rate of burning [2]. Low oxygen concentrations will slow the burning right down, and an example of dangerous fire behaviour that can occur in a situation with low oxygen is called backdraught, where an enclosed fire has used up most of the oxygen and is just smouldering [2]. If there is a sudden influx of oxygen, like someone opening a door or window, the fire may re-ignite [2]. Additionally, different fuels catch fire at different temperatures [3]. The most flammable fuels are hydrocarbons (contain carbon and hydrogen) [3].
Some types of oil, such as gasoline and engine lubricant, can combust easily because they are fuel derivatives of oil. [1] Gasoline is made from crude oil in oil refineries, while engine lubricants are synthetic. [1] Other types of refined oil products include olefins, which are used to make lubricants, waxes, and asphalt. [1] All of these products have a higher combustion temperature than gasoline or engine lubricant due to their uses. [2][3] Diesel engines also have a higher combustion temperature to reduce nitrogen oxides. [2] As a result, diesel engine oils have added detergent and dispersant additives to combat soot, which is a byproduct of incomplete fuel combustion. [2] Natural gas engines also have high combustion temperatures and do not generate soot, so their engine oils have less need for detergent and dispersant additives. [3]