r-mm

I am on the CT shoreline where winter temps hover at freezing +/-, drop to 20 sometimes, 10 very rarely. I do drive in all conditions. I have and do own several flat-tappet vehicles, of which the 964 has the most expensive and unique (air cooled) motor. I didn't over think oil selection for my BMW E30: used Mobil 1 0w-40 winters, 15w-50 summers. Not saying this was a well researched decision just saying the car had a cheap to fix and famously durable straight six so I changed oil often with highish ZDDP formulas and didn't think twice.

When I had my Carrera 3.2 I used Rotella dino 15w-40 year round.

I am frankly unsure what to do for winters with the 964. I like that 15w-50 is specifically formulated for flat-tappet engines and it is relatively close in weight to Porsche's own recommended 10w-60. I have truly tried and truly failed to determine if 15w is too thick for winter mornings. The owner's manual suggests 15w-50 is okay for cars driven primarily below 50f but above 15f.

Any help from winter drivers would be appreciated.

spartansix

I'm in the same area, and I run Brad Penn 20w50.
I changed to Brad Penn 10w40 for one winter and the car cranked a bit faster but I didn't see any real difference in performance once warmed up, so now I just run the 20w50 all year.
I did consider mixing the two to make a 15w45 but haven't experimented with that yet.

r-mm

Thanks for the feedback.

Goughary

I am running Brad penn 10/40 - also switched along w dave above- but still do since there are mornings when it's super cold and i like the idea that the cold startup will hurt less and for less long. But- the car was also a daily until a month ago- and not a daily like "good weather and driven often"...it was "my only car" daily. So it would get cold starts multiple times every day...

newsboy

I run Castrol 5W/50 synthetic year round in Ma.

JasonAndreas

There is a hugely noticeable difference starting the 964 engine filled with 15w50 in below freezing weather compared to a 0 or 5 weight. In 26 winters I did 3 starts with it before switching down to 0w40 & 5w40 for winters (in the berkshires). I don't put enough miles on any of them now to justify switching for winter so I just stick with 10w60 and throw on some Hakkapeliittas.

psiegel

I run Brad penn 15/40 year round and have no problem. I live in Colorado at 9,100 feet