Does multi-grade motor oil thicken?

10w-40 for instance. Not sure I am right here, but my understanding is that 10w stands for 10 winter and means that at 0 degrees the oil will flow at a 10 weight oil consistency. How does the 40 work. As the engine heats the oil up, does it get thicker? Thank you.

 

It doesn't thicken, it just doesn't thin out as quickly. Cold 10-40 is like cold 10, hot 10-40 is like hot 40.

 

Much better answers will be had here: http://en.wikipedia.org/wiki/Motor_


Ooops - I see your Question now: multi-viscosity oils have viscosity improving polymers that DO thicken it as the temp rises - so you were right in your "guess" to start!

(Sorry - must read questions more carefully!)

 

All oils thicken, with the exception of synthetics. Oil thickening up is one of the reasons you have to change it. You want the oil thin so it can circulate.

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This is correct oil does not thicken as the temperature increases.

 

Plenty of misinformation out there.

Read-up, yo: http://www.bobistheoilguy.com/motor-oil-101/

 

bobistheoilguy is my go to place for anything oil related. Lots of good info over there.

 

Thank you for the bobistheoilguy site. More information than I knew existed and actually kind of interesting to read. Thank You

 

Thanks for the link.

Motor oil has been one of those things where everyone you talk to has a different opinion on what's works best.

Here in Florida I like running a straight 30 weight oil.

Jimbo