Cold weather oil viscosity

I'm wondering if anybody up here in the cold Northen states uses 5W-30 in their engines in Wintertime. I've heard that it's a better viscosity in being so that the oil reaches the top of the engine faster upon start-up in cold weather. I'm about to change my oil and just asking if it really makes a difference or not Thanks. 97 GPGT 121,000 3.8

unless you live in an area where it gets REALLY cold for long extended periods, then it could make a difference. I live in Michigan, and run 10W30 all year, and have never had an oil related engine issue.

Yea Rich I'm in Southwest MI and the Winters just don't seem to get as cold as they did 20 years ago. I ran 5W-30 last Winter however I'm going to stick with 10W-30 this time. Besides running a thinner oil may make my small oil leak worse? I don't know didn't notice that last time. Thanks for the reply.

Oil viscosity or which oil to use is an interesting topic. GM's recommendation is to use the lowest SAE viscosity grade oil for the expected temperature range for best fuel economy and cold starting. 10W-30 is preferred in a SII 3800 90 degree engine but nothing wrong with using 5W-30 either. I've used 5W-30 during the winter months in my area (desert Southwest). The temperature range for using 5W-30 is if your temperature range never exceeds 60 degrees F and where the temperature falls below 0 degrees F.

Now this is the fun part and where GM's recommendation contradicts itself. :confused:.........:lol: Pertains to Grand Prix's with the GM 60 degree engines - 3100 V6 and GM cars with the 3400 V6. 5W-30 is the recommended oil to use at all times regardless of the above relative to the 90 degree SII 3800. In another words you can use 10W-30 on these engines if it is going to be 0 degrees and above. :screwy:

I agree Bob, especially since the 3100/3400 engines seem to have more engine fitment issues (piston slap, lifter noises, etc...) than the 3800's, you'd think they'd suggest at least 10w30 in them as well. I would bet it's to squeeze that last little percentage point in EPA fuel economy ratings more than to protect the engine better.

Yea a little confusing, I was looking through my owners manual and it recommends 5W-30 for when then temp doesn't exceed 60 degrees. I suppose it all comes down to personal preference but it is an interesting topic Bob, thanks for the info..

I still use 10w-30 in the cold months. Temps here sometimes dip below zero. I switched to Royal purple 10w-30 and almost instantly noticed a difference. My grandprix starts easier, runs smoother, and gets better mileage with the synthetic oil. The easier starting is really noticable in the colder months.

Rich, I believe it was you one time that posted about synthetic oil and how there were two different types. Anyone know what im talking about with two differenty types of synthetic oil? Whats the difference again, benefits of each, and how does one tell the difference?

I was hoping this thread would not get off track or turn into a debate on dino v. synthetic oil. But it has been awhile since we discussed the issue so let it be. Lets get it on. :grinyes:

I recall we've discussed the issue in the past including synthetic over dino and IMO I agree with Paul that it really does comes down to personal preference and experiences. Plus there are too many variables involved which will include differing opinions. This includes economical and environmental aspects.

For example I use synthetic 10W-30 Mobil 1 in my GTP due to extreme heat and overall performance aspects since I have a modded L67 SII 3800 not because it gets too cold in my area. I believe synthetic oil has the advantage in this area due to reduced internal engine friction and reduced internal engine heat versus dino oil but I would not use synthetic strictly because it is allegedly better or superior for cold weather operation which is wide open for debate.

by dino oil you mean conventional?

I thought there were two types of synthetic, one help seals and the other did something else. I just cant remember anymore.

Thanks for the info bnaylor. Where have you been? Took a couple days off of the forum? Or am I just loosing it?

by dino oil you mean conventional?

I thought there were two types of synthetic, one help seals and the other did something else. I just cant remember anymore.

Thanks for the info bnaylor. Where have you been? Took a couple days off of the forum? Or am I just loosing it?

:lol:

I was out most of Saturday working. Sunday was NFL day. :grinyes:

Yup, dino is conventional. On synthetic I believe there is the regular full type and the blended. If you use synthetic use the real stuff.

I know what Tim was talking about Bob, and it isn't the old Synthetic vs Dyno debate. There are oils out there that claim to be synthetic, because the makers put the crude oil through a process that slightly changes it's molecular structure, so they can legally claim that they are synthetic (since the altered molecule doesn't appear in nature). I cannot remember what brands these are ( I think it was Quaker State and Pennzoil, but I cannot say for sure), but I know Mobil-1 and Royal Purple are both true synthetics, not modified dyno oils.

ok, thanks richtazz and bnaylor, back on the origonal post topic!!!

That rings a bell Rich. Also, I believe Castrol Syntec oil is a blend claiming to be a real synthetic and Amsoil is full synthetic. The biggest give away or indicator is the price difference between the quasi and full synthetics.

But Amsoil disputes Castrol's claim. :dunno: