Driving within the city, typical posted speeds are 50 kph (30 mph*).
A litre (quart*) of oil weighs approximately 1 kg (2 lbs*).
In a front end collision causing rapid deceleration, an unsecured object, such as a litre of oil, can become a projectile. At 50 kph, the 1 kg litre of oil can have a collision mass of 20 kg! That could be very painful, if not lethal! Consider a CORVUS® box for securing your cargo and making your vehicle a safer environment for the occupants.
There are many articles, from reliable source, that address this issue. Many can be found on the internet. Here are some additional resources;
Road Trip America
Canada Safety Council
Ottawa Citizen, March 2010
Don’t forget, without seatbelts, vehicle occupants can become deadly projectiles too!
*Metric/standard conversions are approximate.