Oil for twin spark yet again

[warsch]

I now have two Alfas in my household. One is 2002 156 twinny (2.0 twin spark) with 190k on the clock and which I will be taking on track from time to time. Its manual says the right oil is 10w-40. Another one 2006 147 twinny Selespeed (2.0 twin spark) with 140k on the clock which is just a daily drive. And its manual says it needs 10w-60 despite being the very same engine (well, apart from extra pre-cats).

So I'd love to settle on one same oil for both cars.

Should I go with 10w-60 for both as being better suited for track days and being listed as standard for the other car? Or should I go with 10w-40 or middle ground of 5w-50?

Or am I worrying way too much and any synthetic oil will be just fine as long as I change it on time?

[bazzbazz]

Answered on the ausalfa site.

[Alfapride]

My 147 has 146k km and when I use 5-40 it drinks quiet a bit of oil moving to 10-50 worked out to be much better Penrith semi synthetic is what I use

[johnl]

I was using a Penrite 15/60 "full synthetic" (whatever that really means, I doubt it's PAO). I'm now using a Penrite 20/50 "premium mineral". The only reason to change from 'synthetic' to 'mineral' was an attractive price on the mineral oil (money was tighter than usual that week). I was wanting to try a thinner oil (hot) to see if it might improve fuel economy slightly.

Anyway, the surprising result was/is a dramatic reduction in variator rattle, with both cold and hot starts. Previously there was always quite a lot of variator rattle until the oil pressure pumped up. Now it rarely occurs (to any noticeable degree), and when it does it's a lot less.

Fuel economy? Well it's hard to say definitively, but previously I was getting a computer indicated 8.4 litres per 100km, now I'm getting 8.3. So an apparent small improvement, but this might just be a difference between new vs old oil (with newer oil better sealing the rings and improving compression?), or it might be statistically irrelevant...

My engine isn't a bad oil burner (as Alfa engines seem to go), it uses some, but not a lot. It's hard to say if the oil consumption is worse with the 20/50 oil. In the first week or two it seemed to use significantly more than 'usual', but after that it now seems about the same.

Regards,
John.