The thinking I heard was a thinner oil when cold would protect better on 'dry' starts, even in warm weather. The thought was it would be faster/easier to pump the thinner oil into the bearing surfaces and build oil pressure.

So from that theory, a lower 'cold' number would be better, even in warm weather. 0w better than 5w. Since most engine wear occurs from dry starts, anything that could reduce time it takes to build oil pressure in this scenario would be immensely useful.

Obviously with dino oil a larger spread between lower and upper numbers means additives that can break down quickly. But a good group 5 based synth won't have that limitation.

I don't have any research to back up the idea that lower cold number oil will build oil pressure sooner even when its warm out, but it made sense to me.

 

i do run the dominator series 10w-30 in my track car which is also my daily and i swear by it. i have tried many many different oils in my ap1 from mobil1 to royal purple, dino oil, shell synthetic and amsoil z-rod and i would burn a shitload of oil just driving around. with the dominator 10-30 i do 2 track weekends in between oil changes and not a hint of any oil burning. i dont have a catalytic converter though which would be bad for it if you run this oil. its expensive but in the end its cheaper than a replacement engine or topping off 1 quart every 1000 miles which was the case for mobil 1

 

For what? I am not a dedicated track car nor do I have boost. I would maybe run it if I were boosted or my car saw the track a lot but the Signature is the best all around for their oil. I have used it and it never burns and runs great.

 

I've used it since the car had the first oil change - has 68K on it now.

 

0w oils typically don't become less viscous ("thinner") than their 5w counterparts until temperatures get down to about 0f to -10f degrees. For some reason people think that the first number in 0w30 is the "weight" of the oil when the engine hasn't been started. It's not. The "W" in 0w30 stands for "winter" not "weight", and specifically refers to a test conducted at a temperature of 0f degrees. So if you're using 0w30 oil to combat engine wear at startup, but are doing it in a climate that never sees temperatures that low, you're likely using a thicker oil than you think or is called for.

 

I like their low NOACK volatility numbers on their oils, they are pretty impressive in that regard. I like how they bumped up the anti-wear additives in their signature series oil, they use a nice mix of moly, boron, and zinc, as they used to shun moly in past years.

Amsoil has some really good motor oils, but some of the over the counter brands like Castrol Edge and Penzoil Ultra have really stepped up their game in recent years and offer some competitive products.

 

1. Been using all Amzoil fluids (04 only has 50k miles), and changing them out 1x/yr (only put 8k/yr. on daily driver here in Indy, bought it April 2010 w/9k miles).
2. I get it through a dealer that charges me about $8 for the Signature Series 10*30, and about $11 for the tranny and diff. gear oil; I was checking my latest bill today, and I actually get some of it for a dollar/qt. cheaper, but don't remember which ones.

 

I use it in the diff - 75w-110, but I use Mobil 1 full syn in the motor.

 

You should stop spreading this misinformation.
You should read some more about oil and the SAE J300 spec in particular so you get your temperatures right, to start with.
Sure, the SAE grades are a range.
Sure, depending on the oil composition, you will find (usually cheap and dino) 5W oil that are as thick - or thicker - that real syn 10W oils at the same not-so-low temperatures.
Except for the odd-one-out (AFAIK Castrol 0W-30) true syn 0W oils ARE always thinner and catch up with their 5W-10W counterparts when they get warm.

One other thing: if Castrol uses the description "Highly refined base oil" in the MSDS for their "synthetic" oils.... it's NOT group 5, or 4.
They do not even specify the CAS numbers.
Most likely Hydrocracked Group 3, and that's not bad stuff but no true syn.

 

1. Yes, I have a 75*110 in the garage, as well as some 75*90; I think I bought it off hardtopguy when I was at his house getting some hardtop work done on a used one I got from a tip from this site.
2. I have talked to others who have used Mobil 1 forever, and even use their gear oil, but I haven't seen that in a part's store, but I rarely go into one anymore.