Ik heb in mijn M3 nu Motul 300V 10W40 vol synthetisch zitten. Op zich zou dat net zo goed moeten zijn als die 10W60 varianten alleen even dunner. Gewoon om te proberen, we zien wel wat het doet

ah vandaar...mijn werktemp van de olie bij redelijk rijden is 110celcius en bij racen 120celcius en mijn koelwater 105celcius, vandaar dus...de thermostaat (koelwater) opent ook pas bij 105celcius das hoog vandaar olie temp ook hoge maar gewoon bij dit type blok en vermogen.Bert ///M3 schreef:Verschil zit hem in de viscositeit. 60 is wat dikker. Als je olie echt heet word (140+ graden etc) dan heeft die olie nog steeds genoeg viscositeit voor je motor. Bij halfsynthetische olie kan de olie zelf vaak ook niet tegen die temperaturen, maar bij een volsyntheet kan je bijvoorbeeld 140 graden an sich wel hebben.
Er was hier een tijdje terug eens een draadje over Motul 20W60 daar heb ik eens een stuk van Opie oils in gepost, die had een hele goede uitleg.
Komt er op neer dat ik het nut niet zie van 20W60 tenzij je olie echt zeikheet word. Maar als je gewoon met oliekoeler rijd die de olie netjes 100-110 graden houd zou het niet nodig moeten zijn.
Lagere viscositeit geeft ook minder interne frictie in een motor dus zou ook nog ietsje meer vermogen moeten geven volgens de boeken. Maar ik ben niet zo'n motorenman, dus ik heb geen idee over wat voor waarden het dan gaat, 0,1 PK tot 3 PK ????
Van het voorjaar is er een behoorlijke discussie geweest op m5board.com over het gebruik van TWS 10W60 in de M88/S38 motorfamilie van BMW. Ik citeer even uit een bijdrage van lid 'oilman'.GTRene schreef:vergeet elke keer wat het verschil tussen 40 en 60 is? is 60 voor extremer gebruik?
Voor de gehele discussie (synthetic vs semi-synthetic) verwijs ik naar het originele draadje op m5board.com.Having a read on this thread it seems the debate is more about the use of 10w-60 rather then synthetics vs mineral, thats a no brainer synthetics are better then mineral oils in every way so they win... But you do need to pick the correct viscosity.
Here is a little something I wrote a while ago about the use 10w-60 when it is not recomend for your engine.
10w-60
I get asked all the time "why do you advise against the use of 10w-60?".
Let's get one thing clear, I supply 10w-60 and recommend it where it is appropriate for the engine or the application but conversly I caution against it's misuse!
I have debated this many times on many car forums and I know there are some that do not agree with me however I have never had a reasonable technical explanation why 10w-60 is in fact suitable, it's certainly not mentioned in the handbooks of many modern highly tuned performance cars, with the exception of some Alfa Romeos, some BMW M series and a few other randoms.
Explaining this is diffucult so there may be questions but I'll try my best to explain it in plain English!
Lets look at what oil specs actually mean and particularly the higher number which is in fact the oils SAE number (the "w" number is in fact the cold crank viscosity and measured in a different way) The SAE number is measured by the oils viscosity at 100degC.
Your cars require according to the manufacturers specs, sae 30, 40 and in some cases sae 50, just look in your handbook it will not mention SAE60!!
To attain the relevent sae number the oil has to be at 100degC (no thinner than)
SAE 30 11cst approx
SAE 40 14cst approx
SAE 50 18cst approx
Centistokes (cst) is the measure of a fluid's resistance to flow (viscosity). It is calculated in terms of the time required for a standard quantity of fluid at a certain temperature to flow through a standard orifice. The higher the value, the more viscous the fluid.
As viscosity varies with temperature, the value is meaningless unless accompanied by the temperature at which it is measured. In the case of oils, viscosity is generally reported in centistokes (cst) and usually measured at 40degC and 100degC.
SAE 60 is in fact 24cst viscosity at 100degC!
This is 33% thicker than an sae 50, 70% thicker than an sae 40 and over 100% thicker than an sae 30!
So, what's the problem with this thickness?
Well, this is measured at 100degC and at lower temps (70-90degC) all oils are thicker than at 100degC so the problem is compounded to some extent.
The downsides of such a thick oil (when not specified) are as follows:
Additional friction, heat and wear.
A reduction of BHP at the wheels
Lower fuel consumption
The thicker the oil is the more friction and drag and the more power the engine needs to move it around the engine which inevitably translates to less at the wheels.
So, when do we spec a thicker oil?
Well, you will probably have seen us on occassions recommending a 10w-50 but only in these circumstances.
1. If the car is heavily modded and heat/oil temperatures are excessive.
2. If the car is used on track and heat/oil temperatures are excessive.
3. If it's required by the handbook.
Our criteria for this is based on oil temps as an sae 40 semi-synthetic can handle around 110degC for limited periods whereas a proper synthetic sae 40 can hande 120-130degC for prolonged periods due to its thermal stability.
Once you see more than say 120degC for prolonged periods an sae 50 is adviseable as it is 18cst at 100degC and still 11cst at 130degC! This is in fact the same as an sae 30 at 100degC.
More importantly at 90degC an sae 40 is 15cst, an sae 50 is 20cst and an sae 60 is 30cst!
In a worst case scenario with thick oils (when not required) is that you will experience air entrainment and cavitation inside the bearings at high RPM. Not clever stuff!
I know this is technical stuff but oil is a combination of science and engineering and few people know enough about it to make an informed choice. Just because your mates use it and have had no problems is not a good enough reason to use it, your engine would prefer and benefit from the correct oil.
Cheers
Guy
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