RSG wrote:I did more research online and looks like the oils below are recommended by many VQ35DE owners... posting here for refernce.
- German Castrol 0W-30
- Mobil 1 0W-40
- Mobil 1 EP 5W/10W-30
- Pennzoil Platinum 10W-30
For as long as you change your oil every 3months/3750 miles, a good quality 'dino' oil will do the job. Synthetic oil has uniform molecular structure/size as opposed to 'dino' oil - like sand vs. gravel. There are other advantages of synthetic oil. At 4 months/4000 miles OCI, better use synthetic/synthetic blend. For 6 months/6,000 miles or longer, have an oil analysis (@ $25 at Blackstone) before keeping such extended OCI. Oil by itself does not break down but addtives do.
The definition of synthetic oil in the US has changed, courtesy of Castrol and the US Supreme Court. All of the oils listed above can be legally sold as 'synthetic oil' in the US. Outside the US only German Castrol and Mobil 1 0W-40 can be labeled as true synthetic. The others are considered synthetic blends. Group I/II/III are 'dino' oils with varying degrees of refinements. Group IV (PAO) and above (Group V-polyol, ester) are synthetic oils.
Only Mobil 1 Syn 0W-40 is true synthetic oil (Group IV). Any other Mobil 1 'synthetic oil' is a blend of Group III and Group IV (maybe Group V). True synthetic oils are - M1 Syn 0W-40, German Castrol, Amsoil, Royal Purple, and Redline. Motul also has synthetic oil.
Most engine oils in the market complies with the Federal limitations of 400PPM of Phosphorous (P) to ensure the catalytic converter lasts @ 150Kmiles. But performance oils like GC and M1 Syn 0W-40 are exempted from Federal mandate and can have over 1000PPM. A high level of P is not friendly to the 'cat.' ZDDP (Zinc Diakyl Dithiophosphate) is a common oil additive, Zinc for anti-wear and P as anti-oxidant.
For years, I use 4 months/4000 miles with Mobil 1 'synthetic' 30. This year, I switched to 6 months/6000 miles afte rUOA (Used Oil Analysis) from Blackstone came out good in the 03Q45 and 97I30. I never have had to add oil at 4/4 OCI but at 6/6,the O3Q45 and the 06M35 each needs @ 3/4 quart in between oil change. So in my next oil change, I will probably switch to 40 weight on the 03Q and 06M and maintain 30 weight for the other cars.
All 30 weight oils, at near new condition, have viscosity of @ 10-11 CentiStokes (cS) at normal engine operating temp of @ 212F/100C. A 40 weight oil is @ 14 cS at operating temp. Never use a 20 weight oil in your engine unless it is approved by the car manufacturer as it may be too 'thin' @ 7.5 cS for your engine. A 50 weight oil may be too 'thick' @ 19 Cs. Oil viscosity goes down at higher temp and goes up at lower temp. If your engine is overheating, the oil viscosity drastically goes down with a risk of metal-to-metal contact. For most applications a 5/10W winter rating will do, provided ambient temp is at or above 0F. Below 0F, use 0W winter rating and preferrably synthetic oil. I live in NorCal so a 5/10W-30 is just about right.
Maybe some of you prefer Amsoil and have seen the oil comparison check where it beats the competition (mainly 'dino' and synthetic blends). Ever wonder why true synthetic oils like M1 Syn 0W-40 or GC were not included?