Using unlisted oil weights

[Shemoves]

My vehicle's manual states many different specific oil weights I can use for varying driving conditions. The list is pretty broad, including many from as thin as 5w30 and as thick as a 20w50. It even says I could run straight 40. It does not; however, specifically mention some other weights I have seen such as 15w40 or 5w50. That being said, would it be safe to use those?

My basic understanding would be that if it says I can use a 5w30 and a 20w50, that as long as the first number is between a 5 and a 20 and the second is between 30 and 50, I should be good...am I wrong?

 

[kokopelli]

i think as long as you use something within that range you should be fine.

 

[Gary Allan]

Quote:
My basic understanding would be that if it says I can use a 5w30 and a 20w50, that as long as the first number is between a 5 and a 20 and the second is between 30 and 50, I should be good...am I wrong?


You can include 0W in there too. It's only achievable with a synthetic.

 

[coffee]

Go with PP, Mobil 1 or Motorcraft 5w20

 

[Junior]

Originally Posted By: coffee
Go with PP, Mobil 1 or Motorcraft 5w20


Was that supposed to be sarcasm? Not a very nice thing to do to someone asking an honest question.

Yes, I know there is not very much difference between 5W20 and 5W30 but I wouldn't make that statment without knowing more information about the vehicle.

 

[slipperysam]

I've seen it mentioned several times on these boards that because 5w30 quickly shears down to 5w-20 that you may as well just use 5w-20. Well doesn't 5w-20 shear down as well leaving you rather unprotected with an oil something more like a 5w-10
if there were such a thing.

SS

Honda baby!

 

[Junior]

All I was saying it is too broad of a statement without knowing more information.

 

[mitchcoyote]

You need to give us more information about your vehicle for us to give you recommendations.....

 

[AndyH]

I *think* the original poster has a Subaru WRX (perhaps an STi). Here's what my STi Owner's Manual states for acceptable oil viscosities:

 

[Shemoves]

I do have an '05 STi. My question is not a 'which oil should I run' type question though. I am trying to better understand the relationship between the oil weight rating system and how manuals are written. For example, the manual does not specifically state "15w40" so I was unsure if there was something 'odd' about that specific weight, or if they just didn't want to write down every weight available that would technically work. It sounds like they just went with the common ones and that I could mix/match and use the recommended weights as a range.

LOL at running M1 and/or 5w20.