Different brands

[Patro]

How far can two brands of the same specifications actually differ?

I am trying to decide if using a different oil really matters. And how can one tell?

 

[HerkyJim]

"really matters"... You can't; so just choose a grade and rating oil as recommended by your owners manual and worry about something more important.

My $0.02

 

[Patro]

That's pretty much what I thought...thanks.

 

[Ugly3]

Sure it makes a difference. Some oils "just" make the specs and some exceed the specs. The problem is the differences are generally margional.

 

[TallPaul]

A 10w30 would have a 100C viscosity between 9.3 and 12.5 cSt. A lot of variation just on that one parameter. Take two "high mileage" oils. Valvoline Maxlife 10w30 lists a 100C viscosity of 10.5. Citgo Superguard Ultralife 10w30 lists a 100C viscosity of 12 cSt. Then there is variation in base oil composition and additive types and levels.

 

[Patro]

So how do I decide which one to go with?

Catrol 10w60 racing or Agip 10w60?

Castrol is SL certified whereas Agip is only SJ...but I don't know much else.

PS The car is a 2003 Alfa Romeo 147 GTA V6 3.2L

 

[Pablo]

Patro - what exactly does your Alfa owner's manual call for?

There is a grain of truth in all the answers so far. But until you state your goals and limits it is a very open question. Sure some oils are better in some cars. This cannot be determined by simply reading specifications nor by one UOA.

Insufficient information given to choose one of those two.

 

[Patro]

The owner's manual says to use Selenia Racing 10W 60. But the Alfa dealer here in Singapore always tries to put Mobil 1 in it.

My goals are something to protect the engine under high-revving and some track driving. I will change every 5,000 km (3,100 miles).

My limits are that I don't want to change the oil any more frequently than that.

I know next to nothing about oil so if there is anything else I should tell you please ask. Thanks.

 

[HerkyJim]

So why don't you just use Selenia Racing 10W 60? I say again: why don't you just use what the manufacturer recommends? Why, why, why...?