My summer oil only has about 1500 miles on it. It is Penzoil full synthetic 15w-50. I only drive occasionally in the winter while I am in school. Up until now, it's been relatively warm in Minnesota and I've had no problem with startups. This week, its -10 degrees every day. Is it safe to drive with that thick oil if I absolutely need to use my car? I hesitate to change to 5-30 at this point because it'll be back in the 40's in another month. What must I do?

 

Compare the pour point of your oil with a 5w-30 dino oil, synthetics do help a lot. It might be OK.
Personally I like 5w-40 synth in the winter and have no problems at all in frigid temperatures. Plus draining the oil and filling with $15 worth of Rotella T synth is pretty cheap and easy, no need to change the filter. I guess that is no help now that it's too damn cold to be doing an oil change.

My advice: This is generally not a good idea and next year I'd suggest changing the oil before it gets cold. For now, I'd suggest taking the bus. If you have to drive let the car warm up a good while. That's assuming the pour point of your oil is similar to a 5w-30 dino, if not I'd take the bus. And go to Ruam Mit for Thai food, it's great.

-Joel.

 

let it warm up for a LONG while... while it warms up you'll notice it running rough until up to temp.

 

I used 10w-40 Valvoline in my Scout when I lived in Montana for ten years. If it will crank over and start, let it warm up before driving like Joel said. In my mind this is where a synthetic pays off, better protection in the extremes.

Lou

 

I'm in Northwest Iowa, and its not uncommon to get to -20 at night, i have Zero Trouble with 10w-40 in the winter, it starts pretty easily and warms up quickly.

 

I starts and warms up fairly quickly, I just wanted to make sure I'm not damaging anything. This fall I'm buying a beater for the cold weather so my 944 doesn't have to see snow. Thanks for the info, guys!

 

I use mobil 1 15W50 in the cold, doesn't have any problems. for compairson i checked it's pour point with pennzoil dino 5w30, and the mobil 1 is actually lower, -42 vs -36 C.

 

Relevent topic this morning.

Out here in Mountain Maryland we've got wind chills down at -10. Drove the Turbo S to the office this AM (15-50 Mobil One) with no drama. Stupid freakin, Tow Daddy Chevy Suburban sprung a pretty healthy leak at one of it's power steering hose connections and I was afraid that it would puke massively in this morning's very cold conditions. So here I am with a great big 1989 Flying Doorstop Crate Motor 350/700R4 4x4 beheamoth with a three inch lift kit, deep dish American mags and 31.0/10.5/15 All Weather/All Terrains on it and I'm trundling my good weather pampered baby around in sub zero temps.

Made sure I ran the car long enough to get things up to temp and never got into the boost etc. but GRRRRRRR and BRRRRRRR go toether this morning, nonetheless.

 

Definitely relevant! It has been -15 around here at night with wind chills ten degrees below that. I have Amsoil 20w-50 Synthetic and it starts fine and runs good, just so long as I let it warm up at idle for about 5-7 minutes first. It has a -33F pour point and the Amsoil 10w-40 I have ran before has a -45F pour point. I say leave it in, and let the car warm up some before taking off.

 

I was mistaken when I said Penzoil, I'm actually running mobil1. I've been letting the car warm up for 5 minutes and had good luck so far.

 

All you guys talking about wind chills, fagettabout it. Wind chill has no effect on machinery,
only exposed flesh!

 

my 924S didn't like it... it wouldn't start at -10... (that's not windchill...that's actual temp). I had Mobil 1 15w50. I killed the battery cranking it... put in Mobil 1 0w40, fired right up.