How do you judge how good an oil is?

[ascension24]

People seem to judge how good an oil is by when they put it in their car, they see how good it runs, as in how much power it makes.

But a car is always going to make more power with a thinner oil compared to a thicker one just because of the resistance. Which has nothing to do with how much protection the oil is givnig.

So is there really any way of knowing if an oil is better then another?

 

[vztrt]

There are independant tests that have been done that actually rank all oils in terms of protection. I'll try to find a link.

 

[Tasmaniak]

I determinehow good an oil is before it burns up and discolours.

Like right now, the Subaru is running 5w-30 Mobil 1 Extended Performance (really expensive) But when I drained it after about 10,000km it was only a little more orange then when it first went in.

Meanwhile I put the same stuff (10w-30) in the Jeep and after about 3000km it was jet black. Not happy. It also found every damn oil leak in the motor LOL But then again synthetics are known for doing that. So I tried putting in Castrol GTX 10w-30 after recommendation from a buddy and at the 7,000km mark it was only just starting to turn.

Where the Mobil 1 EP is good is that I can leave it in there for the full three if I choose. Infact I can leave it in there much longer. The detergents are much more robust and take months to break down.

Meanwhile. I have never used a single additive and I never will.

 

[Shounak]

I determinehow good an oil is before it burns up and discolours.

Like right now, the Subaru is running 5w-30 Mobil 1 Extended Performance (really expensive) But when I drained it after about 10,000km it was only a little more orange then when it first went in.

This can be a good measure, but not necesarily. Oil not discolouring isn't always good. It could mean the oil is not cleaning the carbon deposits etc as well as it should. If you found your oil hadn't changed colour after 10k in a petrol car, you should be worried..

Judge an oil on how quickly it burns and how your car feels with it in. You have to use a few different oils to know..

In our 96 Corolla, Magnatec was recommended but it was burning it like crazy and going sludgy after 5k. After switching to 20w-50, it now runs beautifully..

My car though, despite 194,000km, runs perfectly on 10w-50, better then on 15w-40..

So it all depends on how the car feels and how much is burnt (they're the indicators I use)

 

[Tasmaniak]

50? Makes me wonder how the oil pump is still on the side of the motor....LOL

 

[Shounak]

Which car?

 

[jules]

a recognised quality indicator is the API (american petroleum institute, i think) rating. Sx. i think they're up to SJ now. basically oil companies spend $lots being certified to the latest standard, you will still see some oils certified to the older SH (for example) standard.

there is disagreement in the engineering community over whether you need the latest standard. if you drive a VN for example, it will only specify using oil that meets an older API standard, whereas the VE will specify the latest (current) one.

but much of the standard covers environmental stuff like emissions from the oil rather than hard core performance criteria.

put it this way, if the oil doesn't have any accreditation then i'd probably not buy it. i know some of the smaller quality oils have 'equivalence' accreditation where they can't afford to spend the big bucks getting the stamp of approval, but manufacture the oil to the standard voluntarily.

 

[burnz]

This can be a good measure, but not necesarily. Oil not discolouring isn't always good. It could mean the oil is not cleaning the carbon deposits etc as well as it should. If you found your oil hadn't changed colour after 10k in a petrol car, you should be worried..

Judge an oil on how quickly it burns and how your car feels with it in. You have to use a few different oils to know..

In our 96 Corolla, Magnatec was recommended but it was burning it like crazy and going sludgy after 5k. After switching to 20w-50, it now runs beautifully..

My car though, despite 194,000km, runs perfectly on 10w-50, better then on 15w-40..

So it all depends on how the car feels and how much is burnt (they're the indicators I use)

your on the money, this all depends on the condion of your engine
but if your oil is clear after 10k or so question must be answerd
detergent/viscosity is it still oil or is it liqued grease sound stuped but it does have merit :sleeping: :sleeping:

 

[sixshooter]

People seem to judge how good an oil is by when they put it in their car, they see how good it runs, as in how much power it makes.

But a car is always going to make more power with a thinner oil compared to a thicker one just because of the resistance. Which has nothing to do with how much protection the oil is givnig.

So is there really any way of knowing if an oil is better then another?

I determine how good an oil is by how noisey the car starts each morning as the lifters pump up with oil... the quicker they go quiet the better the oil cause the oil is getting to the top of the motor the quickest.