Min motor er en Ca18det bygget af Simon fra Norris Design.
Er kun til weekend sjov
Olietryk varm over 3000Rpm. 7Bar
Jeg har kørt uden oliekøler og har haft køre temp. mellem 80-115 grader og har så brugt Silkolene PRO S 10W-50 Ester.
Jeg har indkøbt oliekøler og regner nu med 80-100 grader og vil derfor skifte til Silkolene PRO S 5W-40 Ester.
Her er kort grunden til mit valg, og nu får jeg nok klø....
Der findes groft set to typer olie
1: En miniralsk der er på Petroleum basis og kommer fra råolie.
2: Syntetiske som er lavet på en kemisk reaktion mellem syre og alkohol PAO (poly alfa olefins) eller Esters.
De er forskælige på 3 vigtige punkter.
1: Hvis vi forstiller os at olie består af kæder på 1-5 led så vil miniralsk olie bestå af kæder med 1, 2, 3, 4, 5 Led, hvor syntetiske KUN består af lange kæder på 5 led.
Hvis vi så igen forstiller os at der ligger 2 bunker kæder på gulvet foran os og vi skal splitte den ad for at komme ind i midten for at få fat i en kage.
Så vil den bunke med flest lange kæder være sværest at komme igennem da de vil binde og låse.
Det er her nogle taler om at en olie har en høj bæreevne.
Efter hånden som olie får tæsk og bliver udsat for høje temp, vil de her kæder blive korter og korter (nedbrudt) og en 5w40 vil i en flow test ligne en 5W30 olie dog med nedsat bæreevne på grund at slidte kæder.
Når alle kæderne er blevet korte så skifter man olien....
Den olie med flest lange kæder som udgangspunkt, er den bedste, stærkeste, dyreste olie.
2: Syntetiske olie tåler meget meget bedre højer temp. end miniralsk olie uden at den bliver nedbrudt.
Jeg har læst at det kun er ester olie der er tilladt i nogle fly motorer.?
3: Syntetiske olie er meget dyre at fremstille, og derfor bliver vi snyt for den gode olie.
For 15 år siden begyndte Castrol at kalde deres delsyntetiske olie
(90%miniralsk og 10% PAO eller Esters) fuldsyntetiske.
Det fik Mobil til at hive dem i retten i USA.
Mobil tabte og Castrol (alle) fik lov til at markedsføre deres delsyntetiske olie som fuldsyntetiske.
I dag er 9 ud af 10 fuldsyntetiske olier delsyntetiske.
Her til skal dog siges at Castrol laver fuldsyntetiske 100% ester olie til gokart og anden motor sport.
Men de er meget dyre og svære at finde..... Så hvis der står 100 syntetisk på dunken er det sikkert en delsyntetisk med 5-30 % syntetisk olie og resten miniralsk på Petroleum basis......
Men hvis der står 100 % ester..... så er det race....
Ex.
Motul 300V Power 5W-40
Silkolene PRO S 5W-40 Ester
Gulf Competition 10w-40 racing engine oil.
http://www.opieoils.co.uk/pdfs/Syntheti ... ineral.pdf
http://www.opieoils.co.uk/pdfs/Syntheti ... ineral.pdf
Nu er der nok nogle der vil sige at nogle motore skal have miniralsk olie....
Rigtigt/forkert
En gammeldags diesel der konstandt ligger på 90 grader når ikke at slide en billig miniralsk olie op før den skal skiftes fordi at den er fuld af syre og sod.
Simon har skrevet denne her om 10w60 olie.
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 for "spirited driving" whatever that is meant supposed mean.
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.
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
Simon
Log ind
Tilmeld
OSS
Søg
