what's the difference in car engine oil and burnable oil for a lamp or...fuel?

Question

i started talking to my friends about car oil and they said it doesn't burn. I asked why, they said "cus your car would explode if it did."
I said "understandable, but whats in it that makes it not flamable like fuel oil?"
they said "it's thicker"
I said "is it a completely different substance? or is it just differently refined?"
they said "it's completely different."

so now I want to know, what is engine oil made of and how is it different from lamp oil or gas?

Answer 1

OK ...

Assuming we are talking about "standard" petroleum oils rather than synthetic basestocks :

Petroleum products basically sit on a continuum:

Flammable
methane, ethane, propane, butane (all gases) Flash Points -50C
petrol (basically C5 - C10) with aromaics and olefins Flash Point -30C
stodard solvent (low aromatics) Flash Point 35C
mineral turpentine (high aromatics) Flash Point 35C
kerosine / jetfuel A1 Flash Point 45C
lamp oil (low aromatics) Flash Point 52C
light heating oil Flash Point 58C

Combustible
diesel Flash Point 62C min
fuel oil Flash Point 80C
light oil (100SUS) Flash Point 190C
mid visc oil (500SUS) Flash Point 220C
high visc oil (Brightstock) Flash Point 260C
Waxes Flash Point > 260C
Bitumen / Tar Flash Point > 300C

In terms of "how are they different", there are a number of ways:

Moving from Flammable to Combustible, flammable products contain small, light molecules (C1 - C15) of low viscosity and low density while combustible molecules are larger (C16 - C40). This makes them both heavier (higher density) and thicker (higher viscosity).

To get a clean burning lamp oil, you also need to remove the aromatic and olefinic components (read benzene rings and double bonds) as these tend to cause smoke. It should have few other components, so that it will burn clean and leave no residue.

For an engine oil, you also remove some of the benzene rings and double bonds, because they make the oil unstable and prone to oxidation and sludging (not good if you want to keep your engine clean). Engine oils also contain additives to remove the acids which form during fuel combustion, antioxidants, detergent/dispersants to hold up soot, antiwear agents, metal deactivators and viscosity index improvers.

So molecular size, paraffinic vs olefinic vs aromatic content, viscosity, additive packages all play a part.

Answer 2

Your friends are idiots. Oil is flammable... try putting some on a rag and lighting it on fire, it will burn for a very long time. Gasoline, diesel, mineral oil, kerosene, natural engine oil, etc all come from the same source: crude oil. The main difference between engine oil and the rest is engine oil has the desired viscosity, somewhat like thickness, and it does not break down as readily as some of the others. It also has added detergents and friction modifiers to clean and further lubricate your engine.

Answer 3

Engine oil is the same hydrocarbon type as gasoline, but with a higher molecular weight, thereby making it thicker. It WILL burn, and quite easily, but at room temperature has virtually no volatility. Surely you've heard of oil tanker fires....?

Differences of interest: Engine oil has a lot of additives to enhance lubricity and corrosion protection. Lamp oil, etc have none of these things precisely so it won't smoke when burning.

Answer 4

Fuel oil and motor oil all come from crude oil... they're just formulated differently. Motor oil actually has the volatiles, the stuff that makes oil burn so well, distilled out of it, to enhance the lubricating properties, and to make it safe to put in engines.

Synthetic oil, which most new cars use, are synthesized from petroleum byproducts, rather than refined and distilled from crude oil.

Answer 5

Engine "Car" Oil must have extremely hot temperatures before it turns into a vapor and mixes with oxygen to ignite. Lamp oil or fuel oil is a much less dense oil that vaporizes at lower temperatures which allows it to burn quite easily.

Answer 6

engine oil is a lubricant and it is not combustible (flammable) meaning it will not have an explosive reaction with oxygen. the chemical composition of the two differ. Gasoline is combustible and reacts with the spark and oxygen and produces exhaust which is carbon monoxide. Engine oil is a more stable compound and therefore a bettter choice for lubricating a car's cylinders.

Answer 7

actually car oil will burn but its takes alot of heat or an open flame to ignite. when you get your oil changed most of the places will recycle it by selling it to companies that will clean it and then in turn sell it for oil burning furnaces. where i live people use oil burners in their shops for heat in the winter, they normally find small truck companies or co-ops that have some old oil to get rid of.

Answer 8

They are all different cuts of petroleum, just have different flash points depending upon the cut from the refining process. All will burn - are combustible

Answer 9

Engine oil

It is thicker.
It will burn but it is made for lubrication, not for burning.

Lamp Oil

Much lighter
Made for burning and may not be good for lubricating at all.

Answer 10

i dont know! sorry