JC - Castrol 20W50 is standard used by many many Alfa owners, including myself. I sounds like your engine is pretty new inside if you're getting a true 20 psi at hot idle. The Alfa owners manual states that hot idle "minimum 7 psi." The low oil pressure warning light comes on at 5 psi, and some Alfa pubs say that an oil pressure warning light at idle is even ok. Max oil pressure is "65-70 psi."

You're engine may be recently overhauled and with a new oil pump, hence the very good pressure. I don't recall at what psi the PRV in the oil pump bypasses oil back to the sump.

 

Is 20W50 the standard nowadays no matter what the owner's manual says? I'm not at home and can't check right now, but I could swear that the '71 manual specifies 10W40 or 5W40. But the spec also varies depending on brand of oil, too, if I'm remembering right, which just confuses me, especially since I don't generally find myself with a great assortment of oils available. Do modern oils make the manual recommendations somewhat archaic?

 

I should have said "defacto" standard. I use Castrol 20W50 because it has historically worked well in my engines. I also use Redline in the transmission, although that's not specified by Alfa either.

 

I should have said "defacto" standard. I use Castrol 20W50 because it has historically worked well in my engines. I also use Redline in the transmission, although that's not specified by Alfa either.

I intend to use Redline in the tranny (and the differential), too, once it's reinstalled, and I understand that Castrol 20W50 is what a lot of Alfa owners now use based on good experience. I probably could have stated my question differently; a lot of people don't follow Alfa's recommendations today (f'rinstance, it seems not too many use the Golden Lodge plugs). It's also not 1971 anymore, and some of what was available then is no longer available, and certainly newer and presumably improved products are available now. (I turned 11 years old in 1971, so I don't remember if 20W50 was even available then.) So maybe another way to ask would be, if Alfa were rewriting the oil recommendations based on what's available now rather than then, what do you think they'd specify?

Actually, never mind that question. I'd rather know why the 20W50 seems to work better. What seems to be the improvement? (Part of why I ask, too, is because I'll be putting oil into a freshly rebuilt engine in a while and I want to be informed before I do.)

 

I know for a fact that Alfa recommended 10-50 Oil for the crankcase in my (87) Spider with the option of 10-40. Try to find 10-50 in the USA. I use Mobil 1 15w50.

Dave