Tento clanek jiz tu v jednom prispevku je, ale bylo by dobre aby byl v navodech a hlavne aby dostal privlastek - Duležité
Clanek nasel Raddy na UK SXOC forum. Je to clanek od specialisty co se zabyvá oleji.Na UK foru zalozil tema o olejich (cca 37 stran, nedoporucuju cist
) V tomto tematu by jste nasli tu citaci co jsem ja vlozil.http://www.sxoc.co.uk/vbb/showthread.ph ... oil+advice
Velmi dulezita sekce clanku je tabulka kde jsou optimalni provozni teploty pro bezne pouzivane vizkozity oleju.
Citace článku:
Might be worth doing a search but i would say a 10w 40 or 15w 40 for everyday driving and if you do track work a 10w 50 or 15w 50,
it is very important to match the right grade oil to your driving style
This is copyd out of the opie oils section and is a good read
All grades of oil are measured at 100degC and this determines the actual SAE viscosity of the oil.
OEM's are aware of this and spec their oils to this requirement i.e. the thickness that the engine needs at 100degC, at all temps lower than this the oil will always be thicker.
So for example on these cars the stock recommendation is sae 30 or sae 40 which means that the engine need between 11cst and 14cst at 100degC as an ideal viscosity.
So we know what the engine needs in stock form but once modding takes place or hard use that causes higher engine temperatures it changes the parameters outside of the OEM's recommended range either for quality or viscosity or both.
If the engine is running excessive temperatures above 120degC then the oil can become too thin (depending on quality of course) through the shearing or thinning down that takes place, in extreme cases this can lead to metal to metal contact. So in these cases we recommend stepping up a grade to compensate viscosity wise.
However many owners who mod their cars add larger oil coolers to keep the oil within reasonable limits and there is once again a danger associated with this - Over cooled oil!
In these cases, the oil can remain too thick due to it never becoming thin enough which can lead to cavitation, air entrainment and in severe cases starvation in the bearings.
The OEM's specs viscosity wise are there for a reason, the engine is designed to run on a particular grade of oil but car enthusiasts always unwittingly change these perameters as far as oil is concerned.
We have had long discussions with Silkolene on this one with regards to the PRO S and PRO R but cannot vouch for other brands of unknown quality, the Silkolene is a very good race oil.
They say you should look to switch from 5w-40 if the oil temps in the sump exceed 120DegC and that the 10w-50 is capable at 140-150degC although at these temps expect to change it on a more regular basis.
The optimum temps at which these oils work is based on the design perameters and oil temperatures. What I mean by this is that you are looking to achieve a certain viscosity, 11-14cst at 100degC, 30cst is too thick and below 11cst is too thin.
I posted this recently and perhaps it will be better understood by reading what I have posted here but believe me 10w-60 is too thick if your engine runs bulk oil temps in the sump of under 100degC, you're better off using a 5w-40 as it is much closer to the correct OEM spec.
............Temp. for 30cSt (Deg. C).......Temp. for 15cSt.......Temp. for 10cSt
5W/40..................71...........................9 0........................117..............
10W/40................70...........................99. .......................118...............
10W/50................80...........................109 .......................130..............
10W/60................89...........................119 .......................142..............
For your cars the optimum temps on the various viscosities listed on the left is in the middle column as this will roughly produce around the correct viscosity for the engine. EG a 5w-40 at 90 to 100degC is perfect.
As for drain periods, they recommend 10 track hours so long as fuel dilution is not excessive or around 9000 road miles.
One of the biggest mistakes modified car owners make is to cool the oil to 90degC or less and use a thick oil like 10w-60.
As I've said before there are big risks with doing this added to the fact it wastes BHP at the wheels and causes more friction, heat and wear to the engine. Many people believe that thicker oils cool better and are better for big turbos but the fact is it's the complete opposite which is the fact!
I hope this helps to explain, my fingers hurt!
Sorry prekladat do cestiny to zatim nebudu, nemam cas ani naladu. Mozna nekdy pozdeji - ale to uz jsem nekolikrat rikal a nikdy nesplnil
Tak doufam ze to prelozi nekdo jiny kdyz se k tomu nedostanu...Jestli jsem to dobre pochopil tak idealni reseni pro ty co maji problemy s prehrivanim oleje je:
- chladic oleje s termostatickym ventilem a olej 10W-40 za predpokladu ze jezdi s autem i v beznem provozu a obcas jedou blbnout na okruh
- 10W-50 pripadne 10W-60 a chladic oleje pro vylozene zavodni nasazeni
Samozrejme s ohledem k těm výše uvedeným provozním teplotám
