CK-4 vs FA-4 - Whats the difference?

[Cygnus_]

Ive seen some literature online, and I am just curious. For those of you who know about it, what are the main differences between FA-4 and CK-4 spec HDEOs? I know that CK-4 is backwards compatible with many of the previous CX specs, but FA-4 isnt. There are claims that FA-4 is supposed to protect as well as CK-4 HDEO oils at lower viscosities. Does this have something to do with the lower HTHS viscosity as to why it isn't backward compatible?

I know up until recently, many HDEOs were dual-rated CK-4/SN, and then many still are. Valvoline Premium Blue and the Fram labeled HDEO is as well. How would the FA-4 spec fit into this? Would it be a bad idea to run it in a gas engine, or at least, any worse than running a non-dual rated CK-4?

 

[Gene K]

A lot of older engines allowed 30 grade but required higher minimum HTHS than FA-4. I believe the minimum for CAT was 3.7 HTHS. For this reason a 30 Grade FA-4 would not be backwards compatable.

 

[bullwinkle]

FA-4 should only be used in diesel engines that were designed to use it, the HTHS is too low. Not sure what would happen in a thin gasoline engine application, but FA-4 is usually pricy & hard to find anyway.

 

[Gokhan]

Ive seen some literature online, and I am just curious. For those of you who know about it, what are the main differences between FA-4 and CK-4 spec HDEOs? I know that CK-4 is backwards compatible with many of the previous CX specs, but FA-4 isnt. There are claims that FA-4 is supposed to protect as well as CK-4 HDEO oils at lower viscosities. Does this have something to do with the lower HTHS viscosity as to why it isn't backward compatible?

I know up until recently, many HDEOs were dual-rated CK-4/SN, and then many still are. Valvoline Premium Blue and the Fram labeled HDEO is as well. How would the FA-4 spec fit into this? Would it be a bad idea to run it in a gas engine, or at least, any worse than running a non-dual rated CK-4?

The only difference between API CK-4 and FA-4 is the HTHS viscosity (3.5 cP vs. 2.9 cP minimum, respectively). All the other chemical and test methods and specs are identical. If your OEM allows HTHS < 3.5 cP, you are good to go with FA-4. Otherwise, don't use it.

Infineum Insight - API Engine Oil Classifications brochure

www.infineuminsight.com

 

[Jaymie]

The above info on ck vs fa is correct as far as I’ve been able to find, I run ck in my Cummins but I doubt Running either in a diesel would hurt anything, I run oil specd for my engine but i Would imagine any diesel oil would protect just fine

 

[Gene K]

The above info on ck vs fa is correct as far as I’ve been able to find, I run ck in my Cummins but I doubt Running either in a diesel would hurt anything, I run oil specd for my engine but i Would imagine any diesel oil would protect just fine

I wouldn't run the FA-4 in an engine not designed for it. Even with 4.1-4.2 HTHS bearing replacememt intervals doubled as they widened bearings through the years. I suspect in an engine without bearings designed for low HTHS you could see significantly shorter replacement intervals with a 3.1 HTHS.