Castrol GPIII

[JAG]

Mineral oils strive to meet GM6094M (possible typo here) while only some synthetics meet GM4718M. The latter is concerned with handling high temperatures while the former is to insure decent cold cranking and/or pumping (I dunno which but you get the idea).

 

[Jim 5]

Originally Posted By: JAG
Mineral oils strive to meet GM6094M (possible typo here) while only some synthetics meet GM4718M. The latter is concerned with handling high temperatures while the former is to insure decent cold cranking and/or pumping (I dunno which but you get the idea).


6094M = Cold pumpability standard.

 

[OilGuy]

and add'l seal compatibility testing I believe

 

[Jason8691]

Does each auto manufacturer test for different things they want the oil to do?

 

[OilGuy]

I would say so. Each engine design is unique and has its strong and weak points. Oil can help guard against weaker design points becoming a problem.

 

[Andrew]

Like everyone, I am not sure what mix of base oils is in major brands nowadays. However, years ago I used to buy the highly regarded Castrol Edge "synthetic" oil at approx $AU 90 per 5L. Now you can buy it discounted as low as $AU 40. I became suspicious and stopped buying it.

Mobil 1 is still around $AU 80 - 90 per 5L as is AMSOIL.

 

[Jason8691]

Originally Posted By: OilGuy
Originally Posted By: tsmay51
Can this be backed up? Personally I don't read too much into gm specs.


Yes, Mobil published independent lab TEOST test data showing how Mobil 1 compares against the #2 "synthetic" in the world in the ability to resist piston deposit formation (Mobil 1 5.3, Syntec 26.4 - less is better). Maybe OEMs value the ability to prevent piston deposits is a key criterion to gain OEM endorsements?

We are all entitled to our preferences. Whether or not we are impressed with past GM vehicles or not, Castrol apparently finds the GM specs important enough to claim they meet GM4718M without approval. Castrol also rushed to reformulate GTX after GM tested and then removed GTX from its approved conventional product list in May.


Wouldnt you only get piston deposits if an engine burned oil? Im not trying to be a smart***, I dont understand what that would matter unless you had an oil burner.

 

[OilGuy]

All engines burn some oil, some just more than others. There's a thin sheen of oil on the cylinder walls as pistons go up and down. On the down stroke, the oil is exposed to the combustion. Additives are metallic in nature and don't burn - and have a tendency to collect and form deposits.

 

[Jason8691]

Ok, that makes sense. Thank you