I'll jump right into it. I have a 2007 350Z HR (that would be VQ35HR), with 22.000 miles. When I got the car 6.000 miles ago I changed the oil and filter. As usual I asked for OEM oil. I got: Nissan Motor Oil Strong X, 5W-30, API SN, ACEA A3/B3.. This oil is made by Fanfaro, Germany. They also make specific oils for Nissan's diffs (and transmissions). Picture bellow. Please note, Nissan does not specify in the manual which ACEA oil to use for 350Z. Though at the dealership they told me Nissan recommends 0W-30 or 5W-30 API SM, fully synthetic. And looking in the database ACEA should be A3/B3. After using this oil, oil pressure was OK - idling warm at 28 PSI. But I noticed if I go for a spirited "Touge" drive oil pressure would drop significantly to 15-16 PSI idling. After research I found out that here in Europe this is not the same oil Nissan Dealers are putting in. Packaging is different and most probably also manufacturer. So I decided I will go with different brand of oil. As per many posts on forums I decided on Mobil1. I know, most of people go with Mobil1 0W-40, but wanted to go with what Nissan recommends - 5W-30 and see how this oil will perform. Mobil1 ESP 5W-30, API SN/SM, ACEA C2/C3. So, how did Mobil1 5W-30 perform on first drive, with fresh oil? Citiy driving would put warm idle PSI LOWER than previous Fanfaro oil after 6.000 miles. Honestly, I am surprised. I would have though Mobil1 will keep the pressure (more) stable. In the end, Nissan is saying 5W-30 should be enough. I also sent oil sample of Fanfaro to the lab and I wonder what will come back. Now I am seriously considering Mobil1 0W-40. It's API CF, SJ, SL, SM, SN and ACEA A3/B3 and A3/B4. And is designed for specifications of "Porsche A40" and "Nissan Genuine Performances". One information - which I cannot get and which would be confirmed by engineers is - would heavier oil could put additional strain on some engine parts IF this engine has tight clearances? Anyone with VQ here, using 0W-40 oil? What kind of pressures it has?