"This is basically the temperature at which the oil sample will start to combust in °F." Consider removing "basically" as it makes the definition sound ambiguous.
Perhaps also consider NOT using °F. Centigrade looks more scientifically literate.
"and dirt that gets sucked in through the engine’s intake system." Technically it gets blown in, as a reduction of air pressure in the intake causes the high pressure outside air to push it's way into the intake. But, perhaps this is best left uncorrected.
Indeed, because if you "corrected" it, you'd have to explain your "correction", and then you'd look like a pedant.
"The TBN (Total Base Number) is a lubricant’s reserve alkalinity measured in milligrams of potassium hydroxide per gram of oil." The reserve additive can also so be Calcium Sulfonate.
Leave it alone. You're saying how the reserve alkalinity is measured. Doesn't matter in that context what the reserve additive is