Date:         Tue, 2 Jun 1998 13:19:14 -0400
Reply-To:     Don Gibbons <dgibbons@PRESRAY.COM>
Sender:       Vanagon Mailing List <Vanagon@vanagon.com>
From:         Don Gibbons <dgibbons@PRESRAY.COM>
Subject:      oil pressure
Comments: To: type2@type2.com, vanagon@vanagon.com
Content-Type: text/plain; charset=US-ASCII

I may get toasted for this but here goes.

"How much oil pressure does my engine need?" I have heard this many times.

Here is the answer: None. Yes, Zero. Your single cylinder Brigss & Stratten
doesn't even have an oil pump. But it will run for many thousands of hours fine.

But, oil pressure in our engines serves only one purpose: to make sure that oil
reaches all parts requiring it. As long as the bearings are effectively immersed
in lubricant the hydrodynamic effects pull a film of oil between the bearing and
shaft keeping them apart and able to support  an incredibly high load. No
pressure is needed or required.

Then why use a thicker oil? Because as soon as the oil gets fed to the very
first bearing some of it bleeds out the edges because of necessary clearance. A
thicker oil will bleed out less and leave more oil in the stream to go onto the
next bearing. After a while too much oil is wasted by the first bearings and
none gets to the last few and bad stuff ($$$)  happens. A thicker oil will also
get pumped more effectively by the oil pump because of the same clearance
effect.

This is why doing stuff like new oil pumps and fooling with the pressure relief
plungers only work for a short time. If your bearings have too much clearance
its only a matter of time till you have to bite the bullet and replace them.

Both of these things must be kept in mind with older engines. More bearing to
crank clearance, more backlash between the oil pump gears, the bearings down the
line go dry and go away. Same thing with the oil filter. A high restriction
filter will let less oil by and into the engine. The factory filter seems to be
a relatively low restriction filter so thats good.

In short: Use the thickest oil you can find for older engines (most of us use at
least something w 50 in summer)  Forget about single grade 30 wt. And use the
factory filter.

Pawling NY

Cars I have: 93 Eurovan MV
                  75 Westy
                  73 Super

Cars I had: 89 GTi 16v
                 87 Syncro
                 83 Rabbit GTi
                 82 Vanagon Diesel (w 83 GTi engine)