Fundamentals of Engineering Thermodynamics 8th Edition

Published by Wiley
ISBN 10: 1118412931
ISBN 13: 978-1-11841-293-0

Chapter 5 - Exercises: Things Engineers Think About: 11

Answer

Both numbers refer to oils viscosity. A 5W-30 means the oil will flow like a 5 weight oil when cold, and a 30 weight oil when hot. Higher viscosity oil does not give you more protection, in today's precision engines with small oil passages a higher viscosity oil might not flow as well as the oil the car was designed for. Go with what the engine manufacturer recommends. Its just the thickness or the "weight" of the oil. Use what is right for your car. It will usually be on the emissions sticker under the hood or the owners manual. 5w 30 is popular for most cars. Some newer cars use the 5w 20. It won't really matter until winter time when the thicker oil will cause the hydraulic lifters to stick open longer than they should and it could cause stalling until it warms up a little bit. Oil get THICKER as it gets colder and THINNER as it get hotter. Like butter, solid when its cold, liquid when it gets hotter. Works the same with most cooking oils

Work Step by Step

Both numbers refer to oils viscosity. A 5W-30 means the oil will flow like a 5 weight oil when cold, and a 30 weight oil when hot. Higher viscosity oil does not give you more protection, in today's precision engines with small oil passages a higher viscosity oil might not flow as well as the oil the car was designed for. Go with what the engine manufacturer recommends. Its just the thickness or the "weight" of the oil. Use what is right for your car. It will usually be on the emissions sticker under the hood or the owners manual. 5w 30 is popular for most cars. Some newer cars use the 5w 20. It won't really matter until winter time when the thicker oil will cause the hydraulic lifters to stick open longer than they should and it could cause stalling until it warms up a little bit. Oil get THICKER as it gets colder and THINNER as it get hotter. Like butter, solid when its cold, liquid when it gets hotter. Works the same with most cooking oils
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.