hi Guys! I've been working at a gas station and doing a little mechanic work myself. The first thing to do between switching to syntetic is to buy 10 quarts of oil . drain the old oil and fill it with synthetic . Let it run for 10 minutes . Drain the oil . change the filter and pour new synthetic oil inside. You only have to do it once while switching from crap-so-called-oil to a normal synthetic like it should be. remember that you can not switch back from syntetic to crap again. (i don't know what the purpose of that, but still...)
I've been using Mobil 1 oil with Bosch Oil Filter
but now i'm thinking to switch to RedLine motor oil. the difference is Mobil 1 - $5 per quart RedLine is $7.5 but it is recommended by Bimmer enthusiasts rather than Mobil 1.
I tried to use an oil Addative as Lucas oil add.. but after a while i added another quart of oil as the addative burnt away.
In conclusion : if you didn't switched to syntetic oil yet you should do it a.s.a.p.!!! You get smoother & quiter engine performance as well as lower running temperature (that is very important) and better mileage!!! Do not expect gain any HP out of it but do - excelency in performance - use 5w30 or 10w30 if the temperature never drops below 40F.
I don't drive a lot so i change the oil after 10 000 miles with rough driving 7-8 thousands is a limit.
(by the way...3000 miles oilchange is a myth) can go on a crapy oil 5-6000 without a doubt.