This slender metal or plastic rod inserts into a tube extending down to the oil pan or transmission housing. Pulling it out, wiping it, and reinserting it allows a mechanic to read the exact fluid level against the minimum and maximum indicator marks stamped on the tip. It also provides a quick visual check of fluid condition, revealing burnt transmission fluid or coolant-contaminated oil.
Pull the dipstick and check if that oil looks like a milkshake before we try starting it.
A milky or frothy appearance on the oil dipstick is a classic sign of a blown head gasket leaking coolant into the crankcase.
Related terms
Oil change
The routine maintenance process of draining degraded engine lubricant and replacing it with fresh fluid.
Transmission fluid
A specialized hydraulic fluid and lubricant used to operate and protect gearboxes.
Wet sump
An engine lubrication design where the entire oil supply pools in a pan directly beneath the crankcase.