OK, but how come everything I read about the GC 0W-30 says that it's a really thick 30W (close to a 40) and it's fine but this Mobile is not? I'm confused.

 

Well, to tell you the truth, you are confused because you are being given advice from old stick-in-the-mud's who are not keeping up with technology. AMSOIL Inc. introduced the worlds first 100% synthetic API rated motor oil in 1972, but back in the 1960's, it was actually beneficial to use a comparatively thick oil, as this held the promise of increased engine protection due to thicker oil films, while using dead dinosaur technology petroleum oils. But then when 1972 came along, AMSOIL Inc. turned the lubrication industry upside down. AMSOIL has film strengths of up to 3,000 psi, whereas even the best petroleum oils have a film strength of only about 500 psi. Film strength is how much pressure it takes to force out a film of oil from between two pieces of metal, so clearly the greater the film strength, the better for your engine. In the old days, the way to increase film strength was to use a thicker dead dinosaur/petroleum oil. But AMSOIL changed all that and for those keeping up with technological advances, using AMSOIL it was no longer necessary to use comparatively thick oils in order to provide superior engine protection.

It is 2007 and not 1968 anymore, but unfortunately, as I mentioned above, sometimes you can't teach an old dog new tricks and their minds are stuck in 1968. Sometimes the grey haired bifocal crowd are not very open minded to new technology, which is unfortunate. A thicker oil, like the product you mentioned, is in fact not as wise a choice as a comparatively thinner oil that will flow faster, transferring heat away from the engine quicker and getting to critical engine parts that need lubricating as quickly as possible on engine starts so as to reduce engine wear and avoid metal-to-metal dry starts. With a good , true PAO based synthetic oil, it is unnecessary to use a comparatively thick viscosity. I have another thread in this forum regarding this very issue about thick oil improving engine protection or not. So if you want the best engine protection, get that thick oil out of your engine and use something better, that flows faster to help reduce engine operating temperatures, extend engine life and reduce engine wear. In your example, for this reason the Mobil 1 is actually the superior performing product to the lower performing Castrol product.

In my own daily driver, in search of superior fuel economy to beat the coming $4 a gallon fuel prices, I am going to be switching over to AMSOIL 0W-20 and again give the proverbial finger to the Big Oil industry! lol


Steve
CEO of Hi-Tech Oil Co.
Distributing industry leading AMSOIL synthetic lubricants for 19 years

 

mobil 1 0w-40 is a thin 40 and amsoil 0w-30 is a thick 30. they both are ok, but steve wants you to buy his amsoil. not to mention oil will "shear" down or wear down to a lighter weight from normal engine usuage.

 

Hi flash. The post was in regards to Mobil 1 0W-40 and Castrol 0W-30 and which would be a better selection. I answered that in depth and made my recommendation for the Mobil 1. I rather thought my post was to the point, educational and of value.

If anyone wants something superior, that is of course their prerogative.

Steve
CEO of Hi-Tech Oil Co.
Distributing industry leading AMSOIL synthetic lubricants for 19 years

 

By the way, I think I should clarify that when I recommended Mobil 1 would be the better choice, I was referring to Mobil 1 0W-30 and not 0W-40. The
0W-40 viscosity is the incorrect viscosity for an Infiniti and has several drawbacks, including reduced engine power, reduced performance, increased emissions, reduced fuel economy, increased engine temperatures and an increase in engine wear. 0W-30 is the way to go.

Steve
CEO of Hi-Tech Oil Co.
Distributing industry leading AMSOIL synthetic lubricants for 19 years

 

The owners manual says any viscosity from 5w-30 to 10w-40 is fine for the G35.

 

That depends on the temperatures experienced. 5W-30 is the preferred viscosity for all temperatures. Using an oil that is too thick can cause many different issues.


Steve
CEO of Hi-Tech Oil Co.
Distributing industry leading AMSOIL synthetic lubricants for 19 years

 

It says above 0 degrees Fahrenheit you can use 30 to 40 weight no problem. The Mobil 1 0w-40 is a great oil, superior to their 30 weight.

 

But it is not the preferred viscosity for the vehicle though. The 5W-30 is. Using a thicker oil than needed reduces power output, reduces fuel economy, increases emissions, causes internal operating temperatures to increase as it does not flow as faster and transfer heat as well as a lighter viscosity oil that flows faster. No need or benefit in using such a thick viscosity.

Hope this helps.

Steve
CEO of Hi-Tech Oil Co.
Distributing industry leading AMSOIL synthetic lubricants for 19 years

 

I hope this helps in choosing a proper viscosity oil.

 

How can it not be "preferred" when it's the range recommened by the Infiniti engineers that designed the engine? The ranges recommended are the ranges that Infiniti prefers us to use.

 

Contact Infiniti and they will tell you. Every engine made has a range of oil viscosities that can be used, but they also have a preferred viscosity that the engineers would like to see used.

 

How about I just look in my owner's manual? It's what I did when I posted in here.