Bavarian-Board.co.uk - BMW Owners Discussion Forum Homepage
Forum Home Forum Home > Technical & Model Specific Forums > General Motors
  New Posts New Posts RSS Feed - Interesting Oil Facts #2
  FAQ FAQ  Forum Search   Register Register  Login Login

Forum LockedInteresting Oil Facts #2

 Post Reply Post Reply
Author
Message
oilman View Drop Down
Bavarian-Board Forum Sponsor
Bavarian-Board Forum Sponsor
Avatar

Joined: 28-June-2004
Location: United Kingdom
Status: Offline
Points: 1053
Direct Link To This Post Topic: Interesting Oil Facts #2
    Posted: 24-April-2008 at 21:25
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
Use the code BAVBOARD and get 10% Club Discount
email: sales@opieoils.co.uk
Phone: 01209 202944
Back to Top
Sponsored Links


Back to Top
 Post Reply Post Reply
  Share Topic   

Forum Jump Forum Permissions View Drop Down



This page was generated in 0.141 seconds.