1991 3.3L Won't start when cold

I have a 3.3L Buick that doesn't seem to want to start when the temp goes below -25 degrees and then won't start again til it reaches 0. It will turn over and sputter a couple of times but won't go. Runs great otherwise and have taken excellent care as it has no problem starting except when it hits that -25 mark. Coolant is rated for -40, and it is getting fuel. Any ideas?

depending on the type of oil you have it can get thick as mollases at that temp preventing the engine from turning over fast enough to start.

what kind of oil you running in it? when it's cold like this i recomend 5w-30 pensoil. if that don't work you could install a block heater and plug your car in when it's cold and they really do work.

Question here what does it won't start mean, cranks too slow, cranks ok won't fire? Should check fuel quality here also, a scan showing proper coolant temp sensor inputs are all possibilies, even poor spark plugs can cause this.

I hope those temps are celcius, not fahrenheit!!! If it's that cold fahrenheit, you need to get a block heater and battery blanket. I agree with Max. Worn tune-up parts (plugs, wires, fuel filter) can cause hard/no-starts at extremely cold temps. When the temps get that cold, the battery has less cranking power and the vehicle requires more juice to start.

Plugs are new as of October, 5W30 oil, with a good battery and fuel delivery. Temps are in Fahrenheit. Its cranking over well just not catching. Starts great as long as it doesn't get below -25 overnight. Found a crack in the top ignition coil casing and suspect this is the problem. Supposed to get near zero tomorrow so it should start then. Had similar problem last year just looking for different ideas.

The cracked coil is definitely one of the problems, and since you don't mention the wires having been replaced (just the plugs), I would suggest a new set of wires also.