Your Oil Questions answered

Simon,

My '89 M3 has just had its engine re-built (+.030 re-bore, new pistons etc etc).

Would you recommend a different oil for the initial running-in period, or should I fill with a fully synthetic 5W-40 from the get-go?

Cheers,

SS7

I just posted this in the M Power Forum and thought it may be useful here as well!

The question was my views on Redline?

Redline.

It may be best that all Redline fans close their ears or look away at this point, you may not like what you read!

Some basics first.

A good oil must be quite low in viscosity even in the cold, so that it gets around the engine in a fraction of a second on start-up. On the other hand, it must also protect engine components (piston rings for example) at temperatures up to 300 deg C without evaporating or carbonising, and maintain oil pressure.

Unmodified thin oils simply can't manage this balancing act. The answer is to use a mixture of thin oil and temperature sensitive polymer, so as the thin oil gets even thinner with increasing temperatures as the engine warms up, the polymer expands and fights back, keeping the viscosity at a reasonable level to hold oil pressure and film thickness on the bearings.

All oils have a viscosity index which is the number indicating that rate of change in viscosity of an oil within a given temperature range. Higher numbers indicate a low change, lower numbers indicate a relatively large change. The higher the number the better. This is one major property of an oil that keeps your bearings happy. These numbers can only be compared within a viscosity range (10w-40 vs 10w-40) but here it the important thing...............

They do not give an indication of how well the oil resists thermal breakdown! (The oil film tearing or shearing)

This is all down to a very important additive called a Viscosity Index improver and it is critical that this is shear stable.

VI improvers like all other things in life vary in quality and this is down to cost and availability.

In other words, an oil can look great on paper and make impressive claims but, unless all the components are of high quality it will fail to perform under the most arduous conditions.

I asked John Rowland the Silkolene/Fuchs Chief R&D Chemist for 40 years to give me his opinion on U.S. oils (including Redline) for

another car club and below was his reply:

Quote:

Simon,

Redline and all U.S. oils. The main problem with these is that all American Oils have "low grade" Viscosity improvers in them. Good ones are just not available in the states due to the fact that they are just not required for the majority of American engines.

The consequence of this is, although the oils look good on paper with high VI indexes etc they have low grade inprovers so they have a tendency to "shear down" causing a lack of back pressure.

For example, the oil you are using may be a 10w-40 but could be operating when hot a 20!

JR

Unquote:

I was intrigued by Johns answer and wanted to know how he knew it was the case in the U.S. that good quality VI improvers were not available. His reply was as follows:

Quote:

We have found it is impossible to source shear stable VI improvers

in the U.S.A. even for ready money!

Unquote:

Bear in mind here that Fuchs/Silkolene is the largest independent Lube Oil Manufacturer in the World and has facilities in the U.S. 

So, there you have it, another expensive oil that is not all it's cracked up to be!

Mis-information abounds in the oil world and looking behind the marketing hype and claims is impossible unless of course you are a chemist and able to look deep into the oils make-up which neither you nor I can do!

This may be the time to tell you all something that you will probably not be aware of.

FUCHS, the parent company of SILKOLENE supplies 30% of all BMW's oils for factory fill. More than 5,000,000 litres per annum so it is probably fair to say that BMW trust them and.................your car has a 30% chance of arriving in this country with FUCHS oil in it!

Sorry If I've offended anyone but I promised to be frank and honest.

Cheers

Simon

Shoestring 7.

I'll presume that you have not put anything in it since the rebuild.

Do not, I repeat do not use semi or fully synthetic for 1000 miles.

You need the lowest grade mineral oil that you can find, a 10w-40, 15w-40 or even 20w-50 with an API of around SF.

You must do this as it is the only way to bed the engine in properly.

Cheers

Simon

Do you reckon I should the Castrol RS 0W40 all year around on my M roadster? Is it any good?

By the way why is BMW recommending (it says on the bottle) that Castrol TWS is THE oil for M5, M3, and Z8?

cheers

Francisco

Fransisco,

BMW recommend "all year round" the following grades:

0w-30

0w-40

5w-40

So yes what you are using looks fine, I would question the change in the summer though as these are "all year round" recommendations.

Hope this helps.

Simon

I would just like to take this opportunity to than Simon for the great advice, and great service that he provides.

I ordered two 5L bottles of Silkolene Pro S 5w40 oil, and it arrived the next day, as advertised.

I am also very pleased with the price that I paid. I won't go into exact details, but 10 litres of very good oil was delivered to my door for a good bit less money than you can get  8 litres of Castrol RS or Mobil 1 from Halfrauds.

I for one will be making future orders

Cheers,

Ian.

 [/QUOTE]

Why? Are the majority of american engines significantly different from european/janpanese engines?. Also what about all the japanese/european cars imported into the states, surely their requirements are the same as they would be for us.

[/QUOTE]

Because "most" American engines are fairly crude/low tech V8's and the like that have low top RPM and are not as highly stressed.

Japanese and European cars imported to the states will be using European oils supplied by their Dealers and some retail outlets.

Cheers

Simon

 Hi Simon, Thankyou for reply, and you are correct.!! H/book suggests choice of 10/30 , 10/40 , 15/40 . or extreme 5/20 , 5/30.Castrol TWS was used at the change which is a 10/60 .

 Can this grade of oil be detrimental to the working of this M Engine, in particular the Vanos defects, believed by many to be Oil related??.

What is your reccomendation for grade please.??