Mailing List flyrotary@lancaironline.net Message #11762
From: Russell Duffy <13brv3@bellsouth.net>
Subject: RE: [FlyRotary] Oil viscosity
Date: Sat, 25 Sep 2004 20:57:08 -0500
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>
Message

Ah-h-h; something doesn’t compute here, at least not for me.  Did you start from the same temp?  Was the air a lot cooler?  More air blowing through the cooler? More oil in the pan?  A slight reduction in viscosity can’t account for the difference.  The flow rate will be essentially the same, as I think your pressure drops confirm; so-o-o-o what makes the heat rejection rate double?

Same temp, same everything.  The only diff was the oil viscosity.   One of the reasons I tried this was because Bruce T mentioned that thinner oil would transfer heat better than thick oil.  Do you disagree with that? 

But it does bring up the question, what is the recommended oil viscosity?  5W30 seems a bit low.

I'm not sure what the RX-8 uses, but 5W30 is the standard weight in almost every vehicle made now.   Bruce's personal suggestion was 10w40, but Mobile One doesn't come in that weight.  As far as I've seen, the choices for Super Syn are 5W30, 10w30, and 15w50.

Rusty



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