Hello Folks,
I used to be involved with biulding professional race motors at a couple of
different shops I worked at. This is some of what I know about oil systems
that is relevant for regular street cars or Dakotas :-)
>I've been using Mobil 1 since my first oil change. My pressure varies
>wildly within the tick marks. High during highway driving and low at a
>stop light. I think I've seen others mention large flucuations even
>regular oil.
This shows signs of being totally healthy. You would normally want about
30psi at idle and about 55~60psi max during use for a regular street
engine. Much less and first the lifters lose thier preload pressure (and
then bad things if it stays low and the engine is working hard), and more
pressure you get oil in places it should not be, like the past the second
compression ring, etc.
Most oil filters have a bypass valve in them to let oil bypass the filter
when the filter clogs (Dodge and Ford is inside the filter, most Chevy is
on the block, etc) What happens in reality is that this bypass valve is a
cheap piece of spring loaded rubber, and thus a great amount of the oil
flow bypasses the filter at all times, no BSing. This is one reason to use
good quality units.
When you use a super thick oil like 20W50 in an engine that was not
designed for it, the oil pressure relief valve in the oil pump sends a
large portion of the oil directly back to the pan since the thick viscosity
doesn't quickly move through the tight bearing clearances, etc. This can
look good to the uneducated eye since the oil pressure gauge is pegged max
all the time, but in reality you have the pressure but not the volume. If
the engine biulder says use 10W30, believe him and use it.
For example I learned that some of the Winston cars used a special straight
20W in their qualifying engines to get that last .1MPH However I do not
know if they still do this as I have been out of the field for a couple of
years now.
And most importantly I learned that Valvoline (at least used to) supplies
the Pep Boys brand oil including the synthetics. This was the same stuff
as their own with a different package, and a much lower price. One shop I
was at used only this, and I have been doing the same for quite a few years
now.
Here are some web sites that pertain to motor oil and to the greatest evil
of them all, Slick50.
Regards
Nicholas
97 CC Sport, 3.9V6 = 4cylinder power/8cylinder gas mileage
http://www.ftc.gov/opa/9607/slick.htm
http://www.bmwscruz.com/tech/tech003.html
http://www.virtual-cafe.com/~john/
AMSOIL/oilfaq1.html
http://www.virtual-cafe.com/~john/AMSOIL/oilfaq2.html
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 12:08:13 EDT