Also, do you have temp / visc curves for some of the popular oils? I did have access to a couple of Castrol ones but cant find them.

MB

 

I agree but they should know.

3.7 is the acceptable minimum for ACEA and API I believe, I need to check.

Cheers
Simon

 

I'm taking professional advice (serious stuff) on Bob's car as it needs some checking but my personal opinion (and that's just mine at this stage) is that Bob's car would benefit from a 5w-40 ester/pao synthetic like Motul or Silkolene as his oil temps are not excessive (the oil is not reaching 120degC) and he's wasting power dragging thick oils around.

We'll see what the gurus have to say as they've forgotten more about the subject than I know!

Cheers
Simon

 

Indeed I do have charts for various viscosities but they are on xl and can't work out how to post or attach them here.

Could email them if interested!

Cheers
Simon

 

If interested in thick or thin debate

http://63.240.161.99/motoroil/

Simon,

Would be interested in your views on above and email of vis.

 

Hi all,
I'm very interested to know what the 'gurus' say about Bobs requirements,I'm still of the opinion that too wider range is to be avoided, but then oil technology changes as does everything and so the chemists may have created more stable polymers...it's interesting for example that Motul now don't advise mixing as per stockcars post...suggesting a change of tack regarding the chemistry of the oils they make...

As an aside,...what is a little strange is that I replied to Simons post that was directed to me by name and it appeared in the thread yesterday afternoon in a different place to where it is now?...The 2nd post where you clear up the role of VI and improvers/basestock types was not there at all!...It now looks like a wierd post after yours...ANYWAY, good thread...In a car like Bobs, or even a lesser spec of motor it's the shearing of a 5w that puts me off using it even though the flow would be better than a 10w..and hence you should get lower temps...that coupled to the narrower range keeps me in 10w40 road...15-50 track territory...never used a 60 rated as I've never seen temps that I thought warranted it...

 

The views of Mr.Haas are on my computer and I've read them on many occasions. It's a shame his ramblings are so verbose (more so than mine even) as they are very technically correct. He's an advocate to thin oils and makes some good points backed up with technical data. Unfortunately too technical for most people to comprehend!

Cheers
Simon

 

Ok, to Sir Bob's car (and others of similar ilk).

I fear that the advice that I have been given will dissapoint many so I'm sorry for that in advance but I would have to say "I thought as much" about the conclusions.

I have notes of a lengthy telephone call to a true expert and 3 emails! I put everything that Bob submitted here to him and he fully understands the modifications.

Before I start, the only question that he has left unanswered is the technical data on the NF Octane Booster which he does not have and would like to see. I have to confess that I'm not sure what element of this addative would affect the oil choice but I suppose that he must be aware of something that could.

So rather than quote verbatum and make this unreadable here is a summary of the key points that are relevent to the recommendation. Please also bear in mind that many of my posts give technical reasons for what I say and therefore I'm sorry if I appear to be repeating myself!

So, I submitted the information in Bob's initial post and this was the reply:

Quote:

There is nothing here that could upset Pro-S 5W/40 or 10W/50 except, possibly, the 1.5ml/lit of ‘NF’. What is NF? Presumably an octane booster, but what type?

I notice that a larger radiator isn’t part of the spec.! More power means more waste heat to get rid of, so engine temps could be high; a reason to select Pro-S 10W/50 I would say.

Unquote:

I then asked when would the switch to a 10w-50 be warranted and this was the reply.

Quote:

The move from SAE 40 to 50 should be made when the engine starts to drop oil pressure at high oil temperatures. With an 5W/40 shear-stable synthetic in a modern engine this shouldn’t happen until the bulk oil temp reaches around 120C.

10W/60 is no benefit in a modern engine, especially when compared to a really shear-stable 10W/50 such as Pro-S, which is less likely to lose viscosity through shear effects.

Unquote:

I then put Bobs answers to my questions forward and whether this would influence the decision to use 5w-40 or 10w-50 and this was his final conclusion.

Quote:

At these temps. Pro-S 5W/40 would be OK. Still no info on the octane booster?

Unquote:

So, there you have it, gratifying? No not really. I respect the knowlege of people here including Bob but this is an out and out oil expert so I have to bow to his superior knowledge when it comes to all things oily.

In conclusion all I can say is give it a try (it's your car and I won't blame you If you don't feel comfortable doing so) but catagorically ensure that what you try quality wise is "top" stuff as the PRO S he refers to is a "Race" spec oil like Motul 300V 5w-40 which has similar properties in comparative chemical tests. Any old 5w-40 won't do!

Phew, sorry it's long again.

Cheers
Simon

 

Thanks for that Simon, coolant temps don't rise significantly, thought I'd stated that, and the Subaru rad is more than adequate at these levels. I have had bad experiences with Pro-S dropping half its idle oil pressure during track work so definately stay clear of that, never tried the Motul, I do have some faith in Motul as a manufacturer so would be willing to give i9t a go as they say. It would soon become obvious whether it was holding up, bear in mind my benchmarks are not based on what its base stock is etc but whether it hold up pressure under extreme conditions. Even at 115 deg C the 15-50 still holds virtually the same idle pressure and hits peak before 1800 rpm. So that would be the yardstick, Pro-R is better in that respect than Pro-S btw, from my experience.

Any way can you PM me the cost for 5 litres of the Motul and I'll put it in the car and take it from there.

No offence meant but the term "expert" used anonomously does not add anything to your comments, a name would add credability assuming its one that would be recognised. That said I will try the Motul, as mentioned I will never use Pro-S again.

I will also openmly and hoonestly post feedback, if it works with pressure holding up (reasonably I wouldnt expect it to be as good as the 15-50) and temps are down then that would be success in my book.

BTW what about bearing loading, my boost levels are much higher than normal, anything of relevnce there?

cheers

bob

 

Hi all,
Don't mean to stand on anyones toes here but in response to the recommendation of PRO-s for Bobs car...I'd say not...as Bob has said I too have seen presure drop off under use with rising temps.Oil was Pro-s 10/50, started dropping presure at around 105-110c measured with defi in no3...This concerned me and I stopped using the PRO-S and now use Motul 300v 10/40...no probs now...The other thing is that as I mentioned earlier , I did some reasearch some years ago now, and I know oil has come on in the mean time but I wouldn't like to think of Bob filling with a 5w with his probable main/big end bearing loads...too big a risk I'd say with that sort of spec...10w for me!...Temps never a problem...

 

Well I said I'd try it and I would but if Simon wants to modify his recomendation then fine, but if I see any sign then its coming out pdq, 10 would be the minimum I'd use based on my own judgement.

you couldn't pay me to use PRO-S again.

BTW the car is going to run at Scooby shootout and TOTB 4 so it had better work.

cheers

bob

bob

 

I said that you wouldn't like the advice Bob.

At least I was right about one thing heh!

The expert was in fact Silkolene's Chief Chemist who has 40 years of experience in building high performance oils.

Bob, YHPM.

Cheers
Simon

PS. The messenger is wounded but will recover

 

I use one rating thinner than recommened...best not to mess with subaru's intended formular...recon they now best, turbos generate masses of heat and energy and thin oil cannot cool bearings enough as it travels over the bearings to quickly...i destoyed a £700 turbo after 1k miles running 5w40 mobil 1 on a 5 gt turbo, learn for yourself the expensive way, or use the rally experience of subaru !!

 

LOL I find it higly amusing that BOBR and the so called oilman oil expert have some differences of opinion

Personaly I would like to believe Bob R who has a realy good "practical" rep withth the scoob gang against any oilmans novelty aproch,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ,

 

Thanks Simon, got your pm, will reply in detail later today when more time, thanks for the info and the offer.

Gents I didn't post in this thread to wind anyone up least of all Simon. I'm just one of those people who like to look in the corners as well as the middle of the room. My whole emphasis has been on the difference between levels of tune, I wouldn't ignore things that I have discovered though, hence my comments re the Pro-S.

Guess sometimes my words are not as tactful as they could be.

cheers

bob

 

Thanks Bob, I look forward to hearing from you.

So, forgetting the debate about Bob's car for a minute and I did not post this thread to wind Bob up either I'm dissapointed at some of the comments here and it shows in a lot of cases just how little some people here know about oil.

I originally posted this thread (read the 1st post) to explain that an sae40 was just that at 100degC regardless of the "w" number. If you didn't understand that then go to page 1 read it again.

I then explained what the "w" number meant but did not post any figures however, here is the second piece to the jigsaw for those that don't understand what it's really all about.

0w-40 is the same viscosity as 5w-40, 10w-40 and 15w-40 when hot (100degC) and of course ALL oils are thicker when cold.

WHAT? You don't believe me! The rantings of a mad man!

AFRAID NOT.................READ ON:

..............Viscosity at 40degC.............Viscosity at 100degC

15w-40..........110cst..............................14 cst
10w-40..........100cst..............................14 cst
5w-40.............90cst.............................. 14cst
0w-40.............80cst.............................. 14cst

There may be a variance depending on the particular oil of around 5cst @ 40degC and 1cst @ 100degC but in essence what I'm saying is that oil is much thicker when cold than when hot and therfore it's the thinning (min to 14cst) that's the key here. Again the second number not the "W" number!

At lower temps as long as you have oil pressure flow is more important to engine wear than anything else!

Hence if you need an sae 40, 5w-40 is better than 15w-40 all round as it affords the same hot protection but gets round the engine quicker when cold as it's not so thick.

Yes that's right a 10w-60 is in fact as follows:

@100degC 24cst
@40degC 100cst (4 times thicker)
@ -30degC 7000cst!

Anyone got it yet?

Cheers
Simon

 

so the problem running modified cars (and even std cars 'hard') is heat problems and lack of lubrication to the crank (mainly Subaru specific here!!)...........................

so you continually berate 10w60 oils and yet you have just posted figures that show the same rating when at 40deg and more protection at 100deg.....................the problem here being what exactly???

will happily use something like Millers CFS10w60 over any Silkolene product, already been there and cost me the T-shirt!!!!!!!!!!!!

confused, alyn

 

Ok, I have a question

Consider that most of us measure the average oil temperature in the supply circuit, under hard use this can easily reach 110-120C. This is after it has been subjected to cooling in the sump and oil/water heat exchanger, there is no doubt that the oil is reaching far higher temperatures locally at highly stressed locations, this is where I want my protection optimised.

Taking an oil with a wide differential such as a 0w-40, this exhibits a lower change in viscosity from 40C to 100C (80>14cst) than for example a 15w-40 (110>14cst)
Is it correct to assume that when the temperature is extended further up to say 130/140C that the 0w-40 will retain a higher viscosity than the 15-40 ?
Extending this further, is it possible that a 0w-40 has better (read higher ) viscosity at extreme temperatures than a 15w50 due to the increased VI stability.


Andy

 

I'd like to mention it again, comparing two similar products 0W/40 and 10W/40 the first one needs more viscosity improvers to achieve the wider viscosity and this is fact not guess!
What is more "delicate" in high temp-high shear conditions?
Viscosity improvers!
So even if both oils have same high temp viscosity index the second one is better at HTHS.
I am sure Oilman agree with the above...
JIM

 

Cheers Jim, I understand that I was referring to high quality PAO/ester oils, some of which claim to have no VI's blended. There is still a range of viscosity 'width' available, presumably dependant on the quality of the base stock ?

Andy

 

Sorry Alyn, I didn't mean to confuse you but posting too much technical detail will just mean that it's not read properly and people won't understand.

You are right, 10w-60 has the same cold crank viscosity as a 10w-40 and yes it is thicker at 100degC. So your understanding is correct.

When you talk about heat, how much heat is the issue. Many tuned engines have oil coolers to keep the oil at lower temperatures when running hard.

What I am raising here (and not berating) is whether sae 60 or lets call it 24cst at 100degC is necessary even in tuned engines.

A good sae 50 will cope with 150degC oil temp and a good sae 40 130 degC so the need for an sae 60 is really not there.

I've posted this before but it's worth mentioning again that an sae 40 oil is thicker at 110deC (12.06cst) than an sae 50 at 140degC (8.25cst).

So based on being able to get good oil pressure and oil temps being reasonable there are simply no benefits to using a thicker oil unless you really have to as you will be creating additional heat through friction and losing BHP at the wheels.

The other important factor to bear in mind is shear stability and for this you need to look at HTHS numbers as these are the most relevent as an oil that shears easily will become thinner more quickly with use. This is very important and numbers can be compared. I'm not sure about the Millers 10w-60 but the last time I looked I think it had a HTHS of 3.7 (perhaps you have a data sheet that's more up to date than mine) whereas Motul 300V 15w-50 has 5.33 and Silkolene PRO S 10w-50 has 5.11, the Millers would lose viscosity more rapidly and this is mainly because 10w-60 is a wider viscosity oil than 10w-50 or 15w-50 and therefore requires more VI Improvers to prop it up, making it more prone to shear.

Hope this explains rather than confuses.

Cheers
Simon

 

Andy, the quality of the oil is key here. High VI numbers are good but it's the shear stability that's key (HTHS Number on some data sheets). You can have a high VI Number oil but with poor (Low) HTHS numbers so although it's a good oil on day 1 it might have sheared back within 1000 miles.

Narrow viscosity oils are always better in service as they don't shear so easily.

Cheers
Simon

 

the thing i find odd with your comparisons is that you aren't comparing like with like........................??

what has the fact that at two different temps, two different oils will have different 'thickness'................

alyn

 

Alyn,

I think the point Simon is making is this: If your engine is running too hot then it is better to improve cooling and use a thinner oil than to just throw a thick oil at the problem and pretend it has gone away.

That's my interpretation anyway.

Andrew

 

Very interesting thread, one guy here happy to take oilmans advice and use 5/40 pro s.

 

Not quite sure even thats 100% correct, the biggest factor you have to look at is that your engine has a turbo, which is OIL cooled, a thin oil will evaporate in the temps that turbo produces, one of the reasons to use a thicker oil is that its more consistant at those higher temps and wont break down.

Tony

 

Tony, do the thicker oils really hold up that much better at high temperatures? Mobil 1 0W-40 has a flash point of 236C, the 15W-50 has a flash point of only 230C.

Take a look at http://www.millersoils.net/ and go to motorsport then competition engine oils. There are three CFS(Competition Fully Synthetic) oils listed, 5W-40 10W-40 and 10W-60. For all three grades they state:

"* Maximum continuous operating temperature 125oC. Intermittent running to 150oC will not cause distress."

No mention of higher viscosity oils withstanding temperatures better. They will be thicker yes, but more stable? Who Knows?

Andrew

 

As I see it you want an oil with a high HTHS number and good flow characteristics to keep temps in check...this tends to be more likely with oils that have a narrower Viscosity range...which is one reason I have given for my own preference towards the 10/40,15/50 type of oil. It's the trade off of maintaining viscosity/shear resistance and having good flow that keeps temps in check thats the tricky balance. The narrower range oils achieve this better. What's the point in having a 0w oil in your car if temps never get so low that you really need it, especially when you consider that its more difficult to engineer stability into such an oil at higher temps...which is where you really need the stability...
Even though you can say modern synthetics are inherently more VI independent, it makes sense to operate the oil across the narrowest range possible....that's not to say I advocte going back to mono grade oils, just that in the same way that a cam only really works properly at one engine speed, and are designed as a compromise, multigrade oils are a compromise of flow, heat dissipation and shear strength stability...If you use a 0/5w rated oil IMHO you are asking for trouble because you are compromising on the high temp performance of the oil...I think it needs to be the other way around...make sure you look after the high temp/stress area....and then use the highest w number that gives good flow on startup/low temps...The type of oil you use doesn't alter that logic semi or fully synthetic...its just that fully synthetic oils should be THE most stable...as Oilman says, narrow viscosity oils are better in srevice...whether or not they are full synthetics...with or without VI improvers....

 

Andrew, have a look at the motul site under 300v http://www.motul.com/uk/produits/index.html
They recommend for certain uses certain oils

Tony

 

I should also note that Millers recommend the 10w60 in 2ltr turbocharged engines, none of the lesser oils state this btw!

Tony