Difficulty: Moderately Easy
Things You’ll Need:
- Vehicle
- Owner's manual
- Money
Step1
Go to your nearest automotive parts store or retail super center. Locate the large selection of engine oil. The viscosity of the engine oil should be clearly labeled on the bottle. This will be a series of numbers and letters, like 10W-30. Viscosity is the measure of resistance of the oil as it is being deformed by stress. The first part of the number in the viscosity rating, (ex. 10W) refers to the weight (10) of the oil and whether it is rated (W) for winter use. The second part of the number (ex. -30) refers to how thin the weight of the oil will be when it is warmed to operating temperature. The oil actually changes viscosity when heated due to the addition of polymers by the manufacturer.
Step2
5W oil is thin oil and circulates quickly. It is used for lower temperatures.
5W-20 oil is used for outside temperatures ranging from -20°F to 0°F.
5W-30 oil is used for outside temperatures ranging from -20°F to 60°F.
Step3
10W oil is thicker than 5W and is suitable for most temperatures.
10W oil is used for outside temperatures ranging from 0°F to 60°F.
10W-30 oil is used for outside temperatures ranging from 0°F to 100°F.
10W-40 oil is used for outside temperatures ranging from 0°F to 100°F.
Step4
20W-20 oil is used for outside temperatures ranging from 20°F to 100°F.
20W-40 oil is used for outside temperatures ranging from 20°F to 100°F.
20W-50 oil is used for outside temperatures ranging from 20°F to 100°F.
Step5
Always check the manufacturer’s specifications for your engine before adding or changing the oil and never mix oils of different viscosity together. Remove one before adding the other and be sure to change the oil filter.
Which oil should you use?
Authority 
Comments
mattlee said
on 7/14/2008 thanks!!
purrfect1969 said
on 7/11/2008 Never knew. Hubby buys all the oil.
FUSILLI1OF4 said
on 7/10/2008 Very informative, who knew? Ha! 5*
lacurcio said
on 7/10/2008 You should make this into a wallet sized chart! great information.
Limowreck said
on 7/9/2008 This is an excellent article. My BF is an automotive professional with a degree in automotive science and he often has to whip out the owner's manual to convince technicians that not all cars are designed for 10w-30. Great info!