So I asked a friend in a British car club about the oil temp question. He
has a masters degree in mechanical engineering, and is a doctoral candidate,
his thesis will be on the internal combustion engine, Here is his answer,
still not definitive, but we're getting closer!
Larry Hoy
http://home.cwix.com/~larryhoy@cwix.com/
> -----Original Message-----
> From: Joseph Beard [mailto:jbeard@lamar.ColoState.EDU]
> Sent: Monday, March 15, 1999 5:20 PM
> To: Larry Hoy
> Subject: Re: Oil temps
>
> What is the safe operating temperature of oil? There are those
> temperatures at which lubricants can operate for extended periods, and
> there are maximum temperatures. Above the service temperature, but below
> the maximum temperature, limited excursions are acceptable. This is what
> I found out today:
>
> From john Heywood's book, "Internal combustion engine fundamentals,"
> (1988) the temperature at the top ring groove in the piston exceeds 480 F.
> The temperature in the crankcase is about 270 F. Good quality mineral
> oils alone can not withstand these temperatures, so antioxidant and anti
> corrosive additives are employed. detergents and dispersives are added to
> keep the insolubales that form in suspension and prevent the formation of
> deposits and varnish.
>
> Shichao Zhou, "Studies of a LHRE w/conventional Lubrication," (1995)
> reports that conventional oils have a service temperature of 350 F.
>
> A lubrication company's brochure lists the service temperature of several
> classes of lubricants:
> Fluoroethers 480 F,
> Synthetic Hydrocarbons 260 F,
> Polyglycols 230 F,
> Esters 300 F, and
> Silicones 390 F.
> Though the suitability of the lubricants for automobiles is not commented
> on. The service temperature of synthetic hydrocarbons in this reference
> is in agreement with the mineral oil temperature limitations of the first
> reference.
>
> incidentally, I have read that in ring deposits, half the deposit is
> comprised of ash from the oil additive while the balance is carbon from
> the degradation of the lubricating oil.
>
> I have not given you a concise, definitive answer, but have told you most
> of what I know on the subject. Bill Wardlow may have some practical
> insight into this, if you want to gave him a try at the next club meeting.
>
> Joseph Beard
> jbeard@lamar.colostate.edu
|