How many quarts of oil do I need to change my drive oil?
Bravo 1.

I usually use a clamp on the hose from the resevoir bottle as far toward the transom/drive as possible, no need to waste all that oil. then is usually a bit less than 2 quarts.

My manual says two quarts... I was just going to post a question regarding drive oil....

I noticed that penzoil sells a 80w-90 gear oil for automotive rears and has the same sae-5 rating or something like that as does the marine outdrive oil... Is this the same stuff, but at just half the cost of the marine version??

Bravo-1 takes about 2 and 2/3 quarts. If it is completly empty.

I ran the Redline heavy shockproof for 50 hours, am trying the Mobil-1 75w90 synthetic. The Redline takes forever to drain and can be messy, so I am trying the M-1 which seems to be popular here.

Are the redline and mobil specific to marine use or are they automotive gear oil?

Dunno, I'm just using quicksilver HP gear lube.

Not specified for that use, but a lot of members are using them with good results. The main thing I noticed with Redline is that the magnet on the drain plug had much less metal on it compared to Merc HP thru 2 x 50 hour changes. The main thing to consider before switching is to make sure your drive has good sealing as these oils may not handle water contamination as well as Merc HP. Hydrocruiser has not been able to find the specs on Merc HP gear oil. Wheras the M-1, Redline, Alisyn specs are well known.

2.8 Qts Plus The Res!!!