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From: halb@tekig5.UUCP (Hal Bates)
Newsgroups: net.auto
Subject: Re: Oil changes
Message-ID: <473@tekig5.UUCP>
Date: Fri, 7-Feb-86 00:12:08 EST
Article-I.D.: tekig5.473
Posted: Fri Feb  7 00:12:08 1986
Date-Received: Fri, 7-Feb-86 21:35:42 EST
References: <395@ncr-sd.UUCP> <465@tekig5.UUCP> <529@mhuxl.UUCP>
Reply-To: halb@tekig5tes.UUCP (Hal Bates)
Organization: Tektronix, Beaverton OR
Lines: 47

In article <529@mhuxl.UUCP> smh@mhuxl.UUCP (henning) writes:
>> Do you really change oil every 7500 miles? You must place a low value
>> on your car. By the time 7500 miles has passed the oil in the crankcase
>> is about 1/2 gas and will not provide worthy lubrication. That is why
>> diesels need oil changes more often; the high compression forces fuel
>> past the rings and dillutes the oil. The same thing happens to a gas
>> engine, it just takes a little longer. The need for oil change is not
>> because the oil is dirty, just dilluted.
>
>I have noticed that after 5,000 to 6,000 miles on an oil change, that I
>am not getting good lubrication to my valves/overhead-cam.  The valve noise
>starts getting louder.  I don't see how a manual can recommend 7500 miles
>when the oil doesn't last that long.  I am talking about Sears Spectrum
>10w-30 in a Volvo 245.  As soon as I change oil/filter, the valve noise
>goes away.

The overhead-cam shaft gets its lube from the engine oil pressure supplying
oil that is forced up through the head, out through samll passages, and 
hit the cam assembly (sometimes). Some motors are set-up with a cam
sprayer. A cam sprayer is a good modification to make to any overhead-cam 
motor. 

Anyhow, as the engine gets hot, the old thinned oil will result in a lower
oil pressure (more severe at idle). If your Volvo has a "good" pressure guage,
notice if this is occurs. If the valves are slightly out of adjustment the 
noise will be more noticable. 

Oil is the life blood to an internal combustion engine. Dont use a 
cheap brand to save some money. And change the filter. I hear that some
people actually use the same filter after the oil change. I suppose the
advertised 25000 mile rating on some filters must work. The consumer says 
"I have only 7500 miles on this filter. Must mean I can reuse this sucker."
I really dont understand how or why the manufactures make that claim. 
It is totally misleading.

I run Valvoline 20W/50 in my comp prepared motor and I run the same oil 
in my street rig also. 
Note - not the Racing oil. Racing oil lacks the detergent, it is good for
high RPM applications (anti foaming and low detergent) but poor for 
long-term motors.

Disclaimer
I do not work for Valvoline. Just been around racing for a few years
and know what is used and what I prefer.

Hal Bates
tektronix!tekig5!halb