Date: Tue, 14 Jun 2005 19:26:12 -0400
From: Malt_Hound <Malt_Houndnospamm*>
Subject: Re: Oil for Saab 99 -84

Pooh Bear wrote: > Craig's Saab C900 Site wrote: > > >>"jb" <> writes: >> >> >>>"Mikael Johansson" <> wrote in message >>> >>> >>>>Hello! >>>> >>>>I wonder how much oil it's supposed to be in a saab 99 from -84 and what >>>>kind it should be? (liters) >>>> >>>>WFR: Mikael J >> >>>hi 3.7 litres (including filter). >> >>>I always ran a good 15/40 mineral oil in the UK..Or maybe 10/30 in colder >>>climes. >> >>Another related point - what do those numbers mean? One is the viscosity I >>think, but I'm not sure what the other one is. > > > As I understand it it's the viscosity cold and hot. You want low viscosity cold so > that the oil gets round the engine and all the bearings fast. When hot you don't > want the oil to 'thin' too much. The numbers relate to the SAE method of > calculating viscosoity IIRC. So you want a low number followed by a higher number. > I have to admit I'm no expert. > > One thing that does puzzle me is the wide variety of grades of Mobil One. I'm sure > there's one that's 0W/60. More routinely 5/50, 10/40 ? Never previously seen zero > in an oil spec like that. Which one to use ? > > Graham > Graham, Yeah, you've got the gist of it. First number is the comparative viscosity of the oil to a *straight* weight oil at cold temps, while the second number is the comparative viscosity to a straight weight oil at high temps. Ideally, oil would be extra thin at start-up and get thicker as the engine temp increases, but that just ain't the real world. So instead we strive to get the widest range between those two numbers that meets with the engine manufacturers requirements and doesn't have so many additives (to achieve these miracles of viscosity) that the stuff falls apart under actual conditions inside the engine. -Fred W

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