What is the best type of oil?

[Wahey]

Really appreciate all the help folks. I didn't expect 4 pages when I came for a look this morning!

 

Just to be sure then:

 

Either Mobil one or Caterham Comma motorsport is the way forwards?

 

Can someone just confirm what rating is best again? 5w-50?

 

The car is primarily used on track and sees very high oil temps, so I am mainly after good oil for high temps. Cold start not a major issue for now. It will be when I change my engine!

 

Is a laminova an oil cooler? Where can I get one from?

 

Thanks

 

Rich

[mav]

With a Laminova fitted, in my experience the oil temperature can still reach 100 deg, I assume you are therefore saying that the extra 20 deg causes this substantial drop in pressure? Are you really sure that 20 degs causes such a great reduction?

---

 

Stu,

 

I do indeed get oil temps approaching 100 degrees on hot trackdays. under these conditions I still have a slight loss of pressure (maybe .25 bar) or so.

 

I still do not understand how you can have issues with one oil and not the other, if filled to the same level etc.

[mav]

Rich,

 

The laminova is a heat exchanger that is fitted into the cooling system.

 

Best place to purchase is Think Automotive - Speak to matthew. Tell him if you are a club member.

 

 

[Peter Carmichael]

Petrolhead, Wahey, Oz7

 

I've marked my recommendations in red.

 

The viscosity recommendations have been shifting about a fair bit. There are some reasons for that...

 

Reason #1: The operating temperatures of the wet sump K are unmanaged and you need an oil that can maintain an appropriate viscosity to very high temperatures.

Reason #2: Religion

 

So, if we debunk the religion and concentrate on reason #1 we can understand which of the many recommendations to run with.

 

SAE viscosity ratings categorise the behaviour of an oil at two temperature points. The W part of the rating is for temperatures as low as -45 degC (the actual temperature varies between the 0W 5W 10W and 15W specs). The main SAE grade is for 100degC. We are more usually interested in operating our engines with oil temps between 40 and 120 degC. SAE specify certain ASTM (American Society for Testing and Materials) testing methods (D5293, D4684, D445 and for 150degC D4683, CEC L-36-A-90 (ASTM D4741) or D5481).

 

Any oil that changes viscosity a lot from -20degC up to 100degC will continue to lose viscosity as temperatures rise further. An oil that has more stable temperature behaviour between cold temperatures and 100degC will have more stable viscosity above 100degC.

 

Let's start with Rover's spec of an SAE40 grade for running the engine. This assumes some properly managed temperatures because the Rover installation has a deeper sump and doesn't suffer from windage in the same way as the Caterham.

 

On top of the SAE40 grade you want decent cold starting, so 10W40 is a minimum spec. 5W40 is better and 0W40 is better still. The viscosity behaviour needs to last for a significant time with the oil in service so you look for a decent ACEA grading on the bottle. ACEA A3 B3 is as good a grade as any of us need.

 

For the Caterham application minmising the change in viscosity with temperature becomes more important. For this reason, if sticking with an SAE40 grade, going for the 0W becomes more important. I therefore recommend 0W40 ACEA A3 B3.

 

There is then a new school of thought that suggests using a temperature stable SAE50 multigrade. The same reasoning applies that you want the most highly temperature stable viscosity behaviour. Looking at the numbers there might be some justification in going for a 5W50 ACEA A3 B3. There doesn't appear to be a commercial formulation with a 0W50 rating, but 0W50 with an appropriate ACEA rating would be better still. With temperatures regularly reaching 120 degrees this is a sensible choice.

 

If you can take steps with your engine to manage your temperatures down close to the water temperature at 80-90 degrees, then a 0W40 is clearly a better grade of oil for all running conditions.

 

Finally a quick sense check on the subject:

 

1. Ambient temperatures are only of any concern if they affect the bulk oil temperature. It's the oil temperature that counts.

2. The viscosity benefits of a 5W50 over a 0W40 are only realised once your oil temperature is approaching or is above 100 degrees.

3. Dry sumped engines don't have half the problems faced by the wet sump engines.

4. Inappropriate grades for a K-series include anything beginning with 15W,20W etc. Also any xxW60. Any single grade oil is rubbish in this application. 10W oils are not preferred.

5. ACEA grade A4 B4 is superior to A3 B3. Any higher ACEA grading exceeds all the standards of the lower grade.

 

Edited by - Peter Carmichael on 18 Jun 2004 10:55:12

[SLR No.77]

In summary, if fitted with solid followers, use Mobil 1 Motorsport or the Comma equivalent etc. If fitted with hydraulics, use standard Mobil 1 or Comma equivalent etc. If there is an issue with excessive oil temperatures (wet sumps), do something about it - ie. a Laminova. Better than an oil cooler in that it heats the oil when cold.

My preference is the Mobil 1 but others may have alternative views.

 

Stu.

 

[Petrolhead]

So, lets see if I have understood this Peter and thanks for your answer.

 

The lower the first numkber and the higher the second number the larger the operating range of the oil

 

If running a wet sump car that never gets thrashed and therfore the oil never gets above 100 degC then use 0w40

 

If running a wet sump car that gets thrashed and the oil temp regulally gets over 100 degC then the optimum would be 0W50 but thats not available so the next best thing is 5W50.

 

Also found this here which confirms what you were saying

 

So the question one should ask oneself is how ofter does the oil temp get over 100 degC?

 

If its only occasionally say 2 days a month ie 2 hard blats would you still opt for the 5W50?

 

Now with SL No 148

 

Edited by - Petrolhead on 18 Jun 2004 11:28:55

[SLR No.77]

Petrolhead - are you able to check your oil temperature? In warm/hot weather, you'll probably clear 100 deg when cruising at 80 mph or so

 

1. Use a quality oil suitable for the job.

2. Fit a Laminova.

 

Even with a Laminova you'll see 100 deg when pushing on hard (85 - 90 mph)

 

Stu.

 

[Rob Walker]

Another factor in the selection of the correct viscosity of oil is the engineering clearances used when building your engine. Some high performance K`s run with greater main and big end bearing clearances as well as solid tappets. These engines are never used in very cold conditions thus Mobil 1 15W 50 is a very popular choice.

[Petrolhead]

Hi Stu

 

I have an oil temp guage,

 

So, as peter said a 5W50 could well be the best all round if running wet sump

 

Having a look on some of the oil company sites Mobil and Comma do not do a 5W50 but catrol do a Super Racing

 

Now with SL No 148

 

 

Edited by - Petrolhead on 18 Jun 2004 11:39:54

[YellowSeven]

Peter,

 

Thanks for taking the time to reply with a very informative and no bulls**t post

 

Cheers

[Petrolhead]

Out of interest Caterham recommend 5W50 if thats of any help

 

Now with SL No 148

[dino ferrana]

Petrolhead the Caterham motorsport oil made by Comma won't be on their site as it is not on general sale. I believe it is a 5W50 and it is available from Caterham.

[Peter Carmichael]

Mobil do distribute a 5w50 Mobil 1 in the US.

[Wahey]

Thanks to Peter, Mav & everyone who posted,

 

I reckon everything I needed to know is now covered.

 

Cheers

 

Rich.

[Steveh7]

that was a can of worms 😬

[Slipper man]

At the risk of re-opening it, those of you who are using Minister's engines: use what the builders recommend. David Minister knows what he is doing, and is not out to sell any particular type of oil. The original recommendation of Mobil 1 15W 50 was because there were lubrication issues with the earlier R500's running on 0W 40 oils, and they were focussed on high temp performance of the oils because most of the faster cars were used extensively on circuits. They have always been happy with thinner 5W 50 oils when available (because of the better start up performance), but the Mobil 1 type was not available in the UK (though it was the standard in France, for example). Having studied the Comma/Caterham oil, they have accepted that as suitable too.

[Peter Carmichael]

The lubrication issues with the R500s were arguably because of the rubbish crank oil feeds and the underspecced bearing materials. I'm really a bit fed up with voodoo oil recommendations.

[Normans_Ghost]

Peter, I've just read your reply to my post, You should read what's written very carfully. I was not reccommending viscosity. I was stating that some oils are repackaged in not-too-clean envoirenments.

 

Your theories are wonderfull, so I suppose you'd be happy to use the correct grades even if they had been packed in a factory full of grit a swarf.

 

Experience goes a lot further in my book than documented theory.

 

You challanged a post of mine before and quoted an incorrect torque for front suspension bolts. I never bothered to get into an argument over it as it's not worth it.

 

I'll trust my 43 years experience in repairing motor vehicles of all types and ages over theory any day.

 

 

 

norman verona

1989 BDR 220bhp

Mem No 2166

Curmudgeon in an Elise, (and 7 and Elan)

 

Edited by - nverona on 20 Jun 2004 19:09:21

[Myles]

Experience goes a lot further in my book than documented theory.

 

Damn and blast! Anybody want my copy of the Joy of S@x? I had such high hopes for it...

 

 

Keep BC free and open for ALL. Membership No. 43xx

 

Alcester Racing 7's Equipe - 🙆🏻™

 

Alcester-Racing-Sevens.com

[Slipper man]

Peter: clearly the bearings used were not ideal, which is why they recalled all the R500's they had sold and fitted higher grade items. Equally clearly there is nothing wrong with the crankshaft oil supply because R500's have shown excellent reliability for the last few years. When was the last case of an engine going pop of its own accord? I can't remember one for at least 2 years. What I was getting at was the fact that when I bought my car, the factory recommended Comma Syner-Z 0W 40, which was not right for the engine according to David Minister. Given that he builds the things, I tend to respect his judgement...

[Peter Carmichael]

Norman,

 

I've re-read what you wrote and I owe you an apology.

[Peter Carmichael]

Keith,

 

I'm still stuck on the "... according to David Minister. Given that he builds the things I tend to respect his judgement" bit of your reasoning.

 

It is an Aristotelean notion that a finite body of knowledge exists to be received from respected sources. It is almost as though the Enlightenment never happened; the daring sedition of Voltaire, Locke and Hume who challenged all individuals (or each other at any rate) to think for themselves; to relate the observed facts to a supposed behaviour; to challenge the assumptions underpinning a thesis rather than selectively coerce facts to fit preheld beliefs. The Earth is flat. Burn the witches.

 

If someone is going to tell me what oil to put in my engine I expect to hear some reasoning as to why that suggestion is sound.

 

Here is an example...

 

In researching this topic, I considered a whole bunch of sources amongst which http://www.tech.plymouth.ac.uk/sme/desnotes/lube1.htm, gives a good, thorough academic treatment. Other sources were more practical and more specific to automotive applications and SAE graded oils.

 

The emerging picture was one where design parameters of load, temperature and speed (in particular) determined the appropriate oil grade. A higher bearing speed, for instance, was stated to need a less viscous oil.

 

A large diameter bearing journal has higher surface speeds than a small diameter journal. A large diameter journal can be narrower for the same bearing area, permitting a more compact engine design. The K-series has notably large bearing journals (the 1.8 big ends are larger diameter than the 1.4/1.6).

 

A narrower journal does however spill oil more readily out of the side of the bearing. By turns, the spillage from the bearing and the higher through flow of the bearing means that the temperature rise in the oil passing through the bearing is minimised. The consequence of running big diameter journals is that you need a thin oil and a higher capacity oil pump; also your bearing oil temperatures will stay closer to the bulk oil temperature.

 

I state this merely as an interesting techy snippet. I've stated my oil recommendations and reasons already. It remains my view that a 15W50 Mobil 1 Motorsport oil is a worse choice than Mobil 1 0W40 oil for all k-series applications.

[SLR No.77]

So a quick oil change at Charlie Brown's won't do then 🙆🏻

[Normans_Ghost]

Whilst Peter's correct in his advice, as far as I can see, no ones asked what the engine is to be used for. If I was racing and wanted the maximum performance and advantage over other similar engines in the class I would run on the thinest oil and reduce oil pressure to 20psi. This would have the effect of reducing friction thereby raising power. Only problem is I would probably have to rebuild engine every race. I only make this observation to point out that there may not be one answer to, what at first, appears to be a simple question.

 

norman verona

1989 BDR 220bhp

Mem No 2166

Curmudgeon in an Elise, (and 7 and Elan)

[Petrolhead]

For a Standard Superlight. It sees fairly high temps on track days and when the oil gets thin it sounds tappety. I would like something that holds together better than whatever is in there now. I was told it is fully synthetic now.

 

I thought we know the engine

 

Now with SL No 148

 

Edited by - Petrolhead on 21 Jun 2004 10:03:18