Excuse my ignorance of these matters but can somebody rank three passenger car motor oils with respect to protection during cold start-ups in -30C temperature based on the following specs?

a) 5W30 Synthetic Blend with -39C pour point and CCS 5800 @ -30

b) 5W30 Synthetic Blend with -45C pour point and CCS 4130 @ -30

c) 5W30 Petroleum with -42C pour point and CCS 6600 @ -30

Well, based on the information given, oil b is the best for cold weather. But I heard that a much better test for cold temperature performance of motor oil is the MRV (mini rotary viscometer) test. Do you have MRV for these oils?

I agree with TallPaul.

Oil b will perform the best out of the three and its usage will result in in better starting capability and lower fuel consumption during warm-up on account of the lower CCS value at same temperature amongst the three choices. The pour point value also provides for a higher safety band of opertaion should the temperature fall below -39 Degrees C.

Regards

Sandy Deeds

Thanks to TallPaul and Sandy Deeds for the replies.

TallPaul, I have the MRV for oil a only and it is 19000 @ -35C

Thanks again!

Yes, that is the problem. Some of the best parameters are not reported on the company data sheets, such as MRV and NOACK (instead of which I settle for flash point), and HT/HS. You might try calling the oil company. Sometimes they will give you some of the other data.

But now we are curious as to what are the three oils: a, b, and c?

The three oils to which I referred are as follows:

a) Valvoline 5W30 Durablend

b) Petro Canada's 5W30 Synthetic Blend (Their passenger car motor oil blend as opposed to their Heavy Duty Blend)Specs are at this location: http://www.petro-canada.ca/eng/prodserv/lubesgreases/6886.htm

c) Pennzoil's Conventional 5W30 Mutigrade

The Petro Canada looks pretty good. Has a nice TBN too for a passenger car oil. May have to look for some of that next time I am in Canada.

I have decided to use the Petro Canada 5W30 synthetic blend for my new Chev Cavalier. I realize some people are of the opinion that because the blends are often nearly as expensive as full synthetic, it would be unwise not to opt for the full synthetic. However, here in this part of Canada the Petro Canada synthetic blend is not that much more than petroleum oil but it is less than one-half the price of the popular off-the-shelf full synthetics. Also, in my case, I used one-third of the savings from the GM price reduction incentive to purchase GM no deductible extended warranty for 160,000 kms (100,000 miles). Also, I normally purchase a replacement vehicle by the time I have about 200,000 kms (125,000 miles) on my vehicle.