German Castrol 0w-30, every 6k~8k miles (when i get around to it)
but i drive slow.. i don't remember last time i pushed the car over 3.5k rpm.. maybe october..

 

Good fundamental question! Most people are familiar with oil's viscosity rating—10W40, for example. However, not everyone knows that the "W" refers to "winter," not "weight." Low-viscosity oils flow better than high-viscosity ones (your 5W)—the lighter-weight (thinner oils to some) fluid is easier to pump and therefore circulates faster through the engine's various galleries. Low-viscosity (30-50), heavier oils also tend to operate better at higher temperatures (than do lower viscosity oils such as your 0-5 or 10W). Multigrade oils (5W/30 for example) typically begin as base oils, such as 10W. Then viscosity-index modifiers (polymers) are added in an effort to stabilize the viscosity. This allows a 10W40 oil to flow like a 10W at cold temperatures and a 40W at higher temperatures. In other words, multigrade oils are formulated to pass viscosity tests across a range of weights (and temps). In the summer, a higher viscosity oil works best since heat thins out the oil: in the winter, a low viscosity oil (0-5-10W) is thin enough to be easily pumped through the system, thereby lubricating the engine much quicker in colder temperatures. For your purposes, a 30 would be a thinner oil than a 50-- but i would be the correct oil for the G in most cases. A 90 viscosity oil, on the other hand, works in the gears. Its thickness protects moving parts but does not require that it be pumped through a system. The oil in your rear-end differential will be a thicker oil. Hope this helps.

 

5qts Amsoil 0w30 every 7500 miles or 6 months and Amsoil EA013 nanofiber oil filter every 25k or 1ry.

 

I usually use Mobil 1 5W30 synthetic with Denso filter and change every 3K as I only drive the car about 8K per year, but I have recently changed to ELF Excellium 5W40 full synthetic and Bosch filter upon the recommendations of the mechanic who works on my Passat wagon. call me crazy, but the car seems to run smoother. probably just in my head.

 

05 G35 coupe (76K)

3 quarts pennzoil yellow bottle, 2.5 quart pennzoil platinum = 6K

5.5 quarts German Castrol = 8K

I check around 4500 miles and usually add 0.5 quart of any oil I have left over (from my stash of ~250 quarts of oil...mostly pennzoil and german castrol some valvoline I got from rebates)

08 Rx350 (45K) I use pennzoil platinum and change at 9K

04 accord v6 (150K) I use 1/2 regular and 1/2 pennzoil platinum at 7.5K

04 odyssey (120K) I use motorcraft 5w20 every 5K (twice a year)

I use the same filter as long as it's under 10K miles.

Another thing, I Auto-Rx my cars every 60K to keep it "clean."

 

Every 20,000 - 25,000 miles or so. I use AMSOIL 0W-30, (recommended drain interval/warranty is 35,000 miles or 1 year), along with an AMSOIL Ea nanofiber technology oil filter, once per year, (recommended/warranteed).