At the risk of being the cause of another oil-war, is that the factory recommendation?
My understanding is the Dexos oil specifications (and other "energy conserving" grades) is they're more about fuel economy than shear stability, or being suitable for longer drain intervals. Your ACEA A3/B4 oils have the shear stability (helpful with the stress a turbo has on such a tiny little sump of oil) and ability for long drain interval (which is ill-advised on Saabs - although the detergent package should help with keeping things clean).
In the BMW world, where I spent a lot of the last decade, it was quite common to see threads like "I Used 5w-30 like the manual says and now my car sounds like marbles in a can!". It would turn out they had used a 5w-30 marked as "energy conserving" (ILSAC/Dexos) rather than one meeting the ACEA A3/B4, and more stringent BMW LongLife standard; in terms of oils in the -30 weight, the latter was at the thick end of that grade.
I'm not sure how the pickup screen and sludge fiasco on the B205 motors affects all this either.
Us americans enjoy or oil wars!
For me, its what they tell me in the ASE liturature.
Gf6 is turbo orientated to prevent LSPI. Which for a turbo engine is the main killer. I would say for the LSPI protection any shearing trade off (gf-5 is also satisfied by gf-6a fully though, so going for an old standard doesn't really work as the oil exceeds theo ld standard and passes all its test... PLUS the gf-6 test that were added. It's a cumulative standard)... Is warranted.
It will survive in a turbo longer, and on old apps it is NOT drain interval as gf6 specifically says it does not extend them.
It also was formulated to specifically preserve chain life/ work with low pressure rings that are more varnish sensative than high pressure/ stop some coking with DI.
In a 2000s varnished engine running gf6 will clean it in a few thousand miles and it won't ever clog things because it's got way better suspension properties. It puts the crud in the drain pain.
The economy is part lubricity. A better lube makes an engine run faster. You can hear a motor switched tick up rpms a bit.
Basically its the same detergent package as GF-5 but with magnesium instead of calcium.
Gf6 was a "problem solver" oil more than many others; dexos was developed because GM was pushing the envelope already.
On this one...
"When they descovered wheat... Some of the ancients still insisted on eating acorns..."
But seriously, if its like the 97 2.0 (I doubt they updated much) my manual just says 5-30 or use synthetic if 10-30. They then put it in the gear box too originally! Saab did not seem to worried on it.
From my experience working on more german cars than anything... BMWs kinda go to pot when you baby them anyways. But when I've seen oil issues, its always dino bones not synthetics/ long drain used to get many brands just like extended coolant... Because people popped in green.
Using the absolute wrong stuff is different than using a high end when the manual wants "generic minimum"
Saabs turbos are very much gen1-2 in tunning. All the lag... Or its sweedish LAAG
BUT that said, I'm old enough to remember when upgrading was an issue. You cant run modern oils on flat tappets without zinc which was pulled "for smog" as it hurts the cat.
The thing being... The word "smog" is the evil demon that old birds don't get lead to using the EGR and such to cool the chamber and get way better power today then back then could dream of.
I swear a 120hp v8 was made that way on purpose anyways.
