Bob (Spidell), what's wrong with mixing viscosities? I ask out of curiosity.
I've done that now for a long time without any negative side effects on
recommendation of an motor oil company.
Eric
Heinsberg/Germany
123ignition dealership
Bob Spidell wrote:
Bob,
I wouldn't do that. While there's great debate on oil, everything I've
read says DON'T mix viscosities. Mixing brands is OK, but you don't
want to do a science project on your freshly rebuilt engine. The oil
companies do a lot of research, I doubt you can do any better.
15psi on a hot BJ8 at idle is not bad at all (unless you're idling at 1,500rpm
;).
My BJ8 sometimes almost pegs the needle on a hot day, slow idling in traffic,
yet I've got over 60K miles and it still runs strong (even with nominal low
compression). With our main bearing clearances, you won't get 40psi at hot
idle, even if you used molasses ;)
BJ8s use a gear oil pump which is less effective at idle. You can install
the
earlier rotor type for better oil pressure at idle, with the loss of some HP
at
high revs due to the resistance of the rotor. If, when you rebuilt your
engine
you didn't rebuild the rocker shaft I'd try that first; might be good for
2-3psi
at idle (max pressure is/should be limited by the relief valve).
I've followed this topic (oil) for years, both for my cars and for airplanes.
I've
experimented with different brands and viscosities for both, and have come to
the following conclusion: buy a decent, name brand dino oil, and change
it and the filter often (I was quite happy with Chevron Supreme 20W-50 at
about $1.20/qt, but my local Costco quit carrying it :(
I met John Schwaner the other day. John is a renowned expert on aircraft
engines and, of course, I asked his recommendation for oil. He said of all
the engines his shop gets the ones that look the best at overhaul used
Phillips
66 dino oil. This is after Mobil, Shell and Exxon have spent millions
developing
and marketing various synthetics and blends that supposedly do everything but
wash your windows ;)
I will say, however, that any car I own with a manual transmission gets
Redline
MT-90.
Oh, and drive your cars--and airplanes--often and hard. They like it ;)
bs
--
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Bob Spidell San Jose, CA bspidell@comcast.net
'67 Austin-Healey 3000 '56 Austin-Healey 100M
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