Engine Oil Weights?

[cristphoto]

I presently use 5-20 Pennzoil Platinum synthetic oil. I've read on this site that similar weight oils can be thicker or thinner (based on a rating number). Is this true? I use the correct weight oil for my car and being from the old school was concerned about using 5-20 after a life time of 10-30 and 10-40. What are these ratings based on (room temp, normal engine temp, or other)? Am I concerned about nothing, meaning the state of the art in quality oil today is they're all good? Thanks. Steve

 

[mechtech]

A rating is a range, not an exact viscosity.
Most xW-20 oils are on the high end, almost a 30.
In the VOA section of this forum, you can find specifics of many oils.

 

[AndyH]

Here is an oil viscosity chart for you, hope this helps:

Also, you might want to read this article:
More Than You Ever Wanted to Know About Motor Oil

 

[lewk]

I guess when its suggested that 5w20 is as thin or pours like water... not TRUE. hmmm...

 

[lewk]

I guess when its suggested that 5w20 is as thin or pours like water... not TRUE. hmmm...http://www.research-equipment.com/viscosity%20chart.html

 

[John_E]

It depends on the engine. Since I have a VW and an Audi, I use 0W-40, 5W-40, or one of the thicker xW-30s.

 

[mechtech]

It sure puts a different perspective to it if you say that a 20W motor oil is similar to an 80W gear oil!

 

[MN Driver]

I've never really understood that gear oil comparison because I have poured 20w-50 from one container to another after pouring some 75w-90 into a manual transmission and the 20w-50 was thinner at room temperature, it's all about the viscosity curve though as they might be similar at high temperatures but they are very different when the temperatures drop.