Winter Oil Question

PorscheGuy79 · PorscheGuy79's Garage

Im heading out tonight to buy some oil for a change on my 79 SC. What do you guys suggest for Chicago climate? 10W-30? Im using synthetic brand because the PO had the Jiffy-Lude or what not sticker on there that said they were using synth with no oil leaks. I just wondering what would be the best weight for the winter months.

Bill Verburg · Bill Verburg's Garage

I would use M1 15/50 it flows very well even at well below zero F

MotoSook · 11-12-2004, 02:43 PM

How about 0W-40? You are going to be driving that car during the winter. It can get down right cold at night sometimes here..15/50 would be OK, but you won't need the topend protection durign the winter, so might as well go for good bottom end protection to help your start up. The 0W-40 has a pour point of -54F.

http://www.mobil.com/USA-English/Lubes/PDS/GLXXENPVLMOMobil1_0W-40.asp

PorscheGuy79 · PorscheGuy79's Garage

Thanks Souk, you're there in the clutch my friend. Heading out right now for some 0W-40

anthony · 11-12-2004, 02:59 PM

The pourpoint for 15W-50 is -45. I think either would be fine but if the car isn't parked outside all night I'd stay with the 15W-50.

MotoSook · 11-12-2004, 03:03 PM

Why?

anthony · 11-12-2004, 03:11 PM

Assuming both oils are sufficient for startup then I'd rather have the heavier oil in an air cooled engine.

MotoSook · 11-12-2004, 03:20 PM

I've got 20/50 dino oil in my Carrera, and it's 50 degrees out today. My oil never got hot enough to open my T-stat. I doubt that the oil will get hot enough in Matt's car to open his t-stat when he's out driving around in January when it's -20 degrees out (with a front mounted cooler!). Hence my suggestion that low temp protection is better than top end protection. Why not give the oil pumps and the bearings the greater advantage. Correction...it's 54 deg. C (!)...

Is 0W40 more expensive than 15W50? And the flash points are about the same...~230 deg. C.

It's really splitting hairs, but Matt is a smart kid...he can choose.

PorscheGuy79 · PorscheGuy79's Garage

I cleaned out Autozone of their 0w-40, I think thats gonna be the better option. My temp gauge right now doesnt get out of the 7 oclock postion so I think a little more heat wont be too much of an issue.

PorscheGuy79 · PorscheGuy79's Garage

Plus I can change it out once track season starts up again, move it up to a thicker oil.

cnavarro · 11-13-2004, 03:55 AM

The 0w40 is much better for the winter. Try pouring a bottle of it versus 15w50 when it's below freezing and you'll never use the 15w50 again in the winter. Another great alternative is a mixed fleet delvac 1 5 w 40. It exceeds all porsche specifications for oil- there's a great thread live over on rennlist discussing this exact topic.

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

Bill Verburg · Bill Verburg's Garage

The difference between M1 0/40 and 15/40 isn't that great
15/40

for cold weather use the # to look at is pour point both are -45&deg C, if it ever gets that cold you have a bigger problem than oil.

911 engines were not designed for light weight oil like the newer cars. Back in the old days straight 30 was used all year round.

rhk109 · 11-13-2004, 08:12 AM

I was under the impression that specific areas of our air cooled engines get really hot. In the winter those few areas that get really hot may not be enough to bring the whole 12 quarts of oil up to a high temp, but I assume those really hot areas still need the protection of a heavy weight oil. For this reason I am hesitant to switch away from my valvoline racing 20W50 in the winter. Any thoughts?