Oil analysis on GT

[teK--]

No particular reason why I'm not running a 0W-40. I just felt 5W is thin enough as we don't get that cold here. Also I wanted to try the thinner hot rating.

In fact the Edge Sports 0W-40 is a true group IV synthetic, whereas the 5W-30 is a group III ultra refined. I'd summise that if running high RPM, hot weather, turbo engine, then the 0W-40 is probably ideal. (Kieran this might answer your question). My NA engine does not have as critical a need for an oil to handle such high temps. It has only done 65,000Kms too.

Notably I found it hard to crack 110degC even in the midst of Summer. Dino oil doesn't start to oxidise until about 115 so I don't have any great need to use a group IV oil.

Something which may be suitable for all year round is the Valvoline Synpower 5W-40. I have not been able to confirm if it is a Group III or IV, or mix of both. It's only $60 for 4L. If it is a 100% group IV I think I've found my new oil.

[teK--]

Oh well, it looked hopeful.... :

#

What group of base oils is used in the formulation of SynPower?

Valvoline uses a mixture of Group III and Group IV basestocks.
#

Does SynPower use polyalphaolefin (PAO) base stocks?

Yes. Valvoline uses a mixture of Group III and Group IV basestocks.

[Kekotic]

So just to confirm, I will only have to buy a 5L container of the oil...I don't want to rock up to Subaru with only 1 bottle of it and get told they can't do the service because I need a 2nd bottle. Should I buy 1 5L and 1 1L?

Also, I rarely drive my car hard Jim, is that going to be an issue in getting a 0W-40 oil?
Will it still be okay for daily driving, what about if it's cold? Sometimes can get to 0 degrees here in the morning in winter....I don't feel like reading a thesis on oil's from a blood doctor right now so I'll just have to trust in your good judgement

Thanks.

[teK--]

5L is more than enough. I just checked your engine holds 4.3L when it is bone dry. When they drain it it never all comes out maybe half a litre remains inside.

Give em a 5L bottle and insist they give you what's leftover so you can keep it for topups. I'd be surprised if you don't get back at least 0.5L unless they seriously overfilled your oil (which is not a good thing as it causes too much crankcase pressure and can cause seals to leak).

0degC is not cold at all. In the Alpines etc it gets to -10 or lower

Check your owners manual to see if they recommend 5W-30 as acceptable for every day driving and most temperature conditions. In that case I would use that oil there is no need to go thicker.

[coyote]

Chaotic,

Subaru recommend you use a 5W30 oil.

Viscosity specs can be found here:

http://www.infineum.com/Documents/API/S ... 202008.pdf

A 30 grade oil of similar quality to a 40 grade will be better for your engine under normal operating conditions. The only rationale to go to a 40 grade is for the increased high temp / high shear rating when you are driving a modified engine on the track. Note that you compromise the normal operating specs to achieve this and it is possible to buy a 5W30 oil that meets 5W40 ratings at high temp / high shear anyway.

The oil I use is 5W30, has viscosity at 40C of 67, at 100C of 11.7 and at 150C (and high shear) of 3.5 - meaning it meets 5W30 spec under normal conditions, but acts like a 5W40 (actually almost a 50 or 60 weight oil) under harsh conditions.

If you have a standard car that is not driven on the track, any good quality 5W30 will do (such as Castrol Edge Sport). If you are going to modify the engine and drive the car hard, a 5W30 will still do the job, but you'll need one that that has a higher HTHS viscosity.

I could talk more about other important properties, but it's late the laptop battery is just about flat!

[teK--]

^^ Mobil Delvac?

[coyote]

^^ Mobil Delvac?

No, but there are a bunch of different Delvacs anyway.

Didn't want to talk about the brand, that's why I just posted the viscosity.

Also has a TBN of 12, Noack rating of 7% and high viscosity index for it's spec. These things relate to resistance to acid and change in volatility, which are very important. It doesn't just matter what the oil is like when it goes in, but also what it's like when it comes out.

I think any oil with those kind of specs, regardless of brand, will do a good job.

[Kekotic]

Okay thanks Coyote and Jim, looks like Castrol Edge 5W-30 is the way to go seeing as I don't plan on doing any track work.

[teK--]

^^ Mobil Delvac?

No, but there are a bunch of different Delvacs anyway.

Didn't want to talk about the brand, that's why I just posted the viscosity.

Also has a TBN of 12, Noack rating of 7% and high viscosity index for it's spec. These things relate to resistance to acid and change in volatility, which are very important. It doesn't just matter what the oil is like when it goes in, but also what it's like when it comes out.

I think any oil with those kind of specs, regardless of brand, will do a good job.

That is what attracted me to the Amsoil since their TBN are often up to 12 or more and VI 170+ whereas group III oils around 8 or 10 TBN if very good or it's a III/IV blend.

Tony do you know at what temp Noack rating really comes into being and advantage? Are we talking at the temp that oil starts oxidising or is it earlier?

[coyote]

Tek,

The test is done at 150C, same as the HTHS. I don't know how that relates to oil at 120C, but would think it fair to assume there is some correlation.

All API SL rated oils lose 15% or less.

I just read the earlier post and I didn't write it very well. Suffice to say, you're looking for oil that comes out as close to the same spec as it goes in.

The only way to know that for sure is oil analysis, but the standard tests are a good guide.

[tangcla]

Is the weight rating the same for 2.0T and 2.5T?

No idea what's being used in mine... I'm guessing 5W40 or maybe 10W40? *shrug*

[teK--]

Thanks Tony.

Your original post made perfect sense, I was just curious as to what temp Noak rating is tested at. After a bit of googling, 150degC appears to be the test temp.

Since mineral oil oxidises at 115C and synthetic at 125C, then I believe at those respective tempatures there is already the first stages of oil loss due to oxidation. My understanding is that the Noack test is intended to simulate the temps at the piston rings, whereas whenever we measure oil temps it's typically in the sump.

The interesting question is when the oil is at 110C in the sump then how much higher is it in the block? It would vary from engine to engine of course in which case I would agree that a UOA would be the only way to tell if it has been too hot.

[teK--]

Is the weight rating the same for 2.0T and 2.5T?

No idea what's being used in mine... I'm guessing 5W40 or maybe 10W40? *shrug*

Castrol site suggests either 5W-30 or 10W-40 as suitable for your 2.0T. If you're just driving on the road I'd use the lighter oil.

[tangcla]

Yeah just road. Lighter sounds a good option to me, though probably a bit late, now that the worst of winter is over!

[tangcla]

I think my mechanic put in 15W50 last time... the information provided in the Ferrarichat thread contradicts with what my mechanic says, his opinion is that thin oil will burn, and an older engine like mine (over 100K kms) will have wear and tear issues to consider.