Interesting Oil Facts #2

O

Oilman

Banned
At which temperature does an oil flow better?

There is no temperature where oil suddenly starts to flow better.

A 10W/40 for example will flow between -25C and 100C or more, but there is some difference in the rate of flow! (True viscosity at -25C is about 7000 Centistoke(cSt) units, dropping to 14 at 100C. ‘Viscosity’ is really just another name for ‘rate of flow’.)

The correct question is at what (sump) temperature is an oil at a viscosity that suits a modern high-RPM engine? Present day designs are happy on an oil viscosity of 10 to 15 cSt. (But many are OK on less than 10.) 30cSt is too high at high RPM. It can lead to foaming, air entrainment and cavitation.

Temp. for 30cSt (DegC)..........Temp. for 15cSt ............Temp. for 10cSt

5W/40.........71.............................90.................................117

10W/40.......70.............................99.................................118

10W/50.......80............................109................................130

10W/60.......89............................119................................142


As you will see from the above table a 5W/40 or a 10W/40 is perfectly adequate for all engines except those that run unusually high temperatures (120degC plus)

Cheers
The Opie Oils Team
 
Presumably your ref to high revving engines means as in petrol? What is your view on merits or otherwise of full synthetic v. semi these days? I run diesels and tend to use something like a 5/30 5/40 full synthetic and flush the oil prior to the first change after purchase. (I will be honest and say i normally use Millers oils because they are quite near me and can buy direct!) With flushing I have had suggested elsewhere to drain the oil, refill with cheap oil, run engine for a few minutes until hot, drain and refill with good stuff rather than using flushing additives. Any comment?
 
Dont bother with flushing oils or additives, regular oil changes with quality stuff will keep it tip top.

Synthetics vs mineral, synthetic every timne for me as they are btter in every way for both petrol and diesel.

Cheers

Guy.
 
Adrian888, just be sure you use the correct spec for the A2 1,4 TDI pumpe düse diesel (PD) engine. VW 507.00 for variable intervals or VW 505.01 for fixed. If you don't, serious engine damage might occur due to the high pressure in the PD engine .
 
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