Oil for Saab 99 -84

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.

My C900's which have B201 engines have both just had oil/filter changes (the

1985 900i had awful oil - must have not been changed by the previous owner for a while), and I've use Shell Helix Ultra to replace the old oil. Some of the SCCA members I've asked about oils have recommended it, so while it's not cheap (A$55 for 5 litres), I figure it's going to be better for the engines in the longer term.

Both engines had an oil flush product added and the engine run until it was warm before draining.

On a related issue - it's interesting that people are talking about 99's made in 1984. Did 99's post-1980 make it into all of Saab's markets at the time, or only in Europe?

Regards,

Craig.

Another related point - what do those numbers mean? One is the viscosity I think, but I'm not sure what the other one is.

Regards,

Craig.

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