Wow, so many opinions. I'll add mine. Now, I just bought my first 928 (early '86). But I've been driving 35 years. What dad told me: Use name brand oil (I like Castrol). Use the grade that the guys who designed the car recommend. Change it often (I like every 2000 miles myself, 1000 on the motorcycles). Filter too, every time. Give your engine time to warm up before driving away. Pre fill the new filter before putting it on. When changing the oil, warm it up good first, and give the bad, old worn out oil plenty of time to drain out. Check your oil EVERY time you get fuel, or at least once a week (I don't see anyone doing that anymore, and that goes for all other fluids the car needs as well). Lubrication, you can't change it too often. I've had many cars over 200K miles, two over 300K. Zero engine problems related to lubrication, with aluminum and iron parts. None ever needed to have their engines apart. Yeah, the main bearing seals start to leak as the miles increase, and the gaskets need to be replaced, but never had a problem with burning oil as far as I could tell from the exhaust (no smoke), and they all passed emission inspection. So I guess I did something right. So the simple advice of giving the engine plenty of fresh, clean, cool oil seems to work just fine. For my shark, I'm going to go with 10W-50 Castrol, maybe the 15W-50 in the summers. Now, it is starting with 70,000 miles on it, we'll see as time goes by how me and my shark make out with this routine.

 

IMO, you should *never ever* put anything less than a 50 weight oil (when hot) into a 928 unless you live near an icy tundra. If you do, you're just asking for trouble. Just because Porsche now recommend 0W-40 (or is it 5W-40) in all their cars doesn't mean it's necessarily good for them, especially the older ones. The main reason is that it causes less internal engine friction which gets you slightly better gas mileage and saves Porsche some points in the DOT vs. car manufacturers cat and mouse MPG game. But, again IMO, this is at the expense of good viscosity (and therefore lubrication) under hot running conditions. The pour point of Mobil 1 15W-50 is excellent until ~30F, so unless you live somewhere where it gets colder than that for extended periods of time, you should be using an oil like that.

On a related note, if I ever saw the oil pressure dip so much as to turn on the pressure warning, I would immediately take the car home, buy some xW-50 oil and change it without driving it another mile. I've owned my 928 for 6 years now and put over 60k miles on it, and the engine sounds and runs today as it did when I bought it. 177k miles and counting...

Dan
'86 928S 5-spd w/LSD

 

93 race days, amzoil! still running! 5 bar when hot at 3000rpm

mk

 

It's the same oil too!!!! He never changes it!!!!