Best oil for a 120k mile engine?

[gmcdougal]

i have an 02 qx4 with 120k miles. The engine is burning some oil. When i bought the vehicle 4k miles ago i put pennzoil full synthetic. should i continue buying this or is there a better oil solution for higher mileage vehicles?

[alexf20c]

are you burning it or leaking it? how low does it get every oil change?

[Kompresshun]

Here's what i've been told by Infiniti, I had the same problem with our '02 burning oil. I took it in for service and they told me it was 2qts low... They told me that for some reason the 3.5L doesn't like to run synthetic oil and that the QX4's come from the factory with conventional dyno oil in them, they recommended Valvoline(which I prefer already anyways). They said that the 3.5L burns synthetic but it doesn't burn conventional oil, so ever since that i've run high mileage Valvoline in it and haven't had any issues for the last 4 oil changes(12,000 miles).

[gmcdougal]

interesting...guess ill give valvoline high mileage a try. its gotta be burning it. i dont see or smell any oil and my driveway stays oil free.probably went through 2 quarts in 5k miles.

[fueler]

synthetic oil has a thinner consistency than regular dinosaur oil so it passes through seals and piston rings easier than the cheap stuff...

[Qxxx4]

I was using semi synthetic n had to top up every few hundred kms now with castrol high mileage regular oil I get a good 3000kms before it needs a good 1L top up

[fueler]

dang thats crazy... my qx4 with 180k miles has never needed a top-off...

[WPGQX4]

Synthetic oil has the same viscosity as conventional oil in the same weight.5w30 is 5w30 weather its synthetic or conventional. Now Viscosity break down is different and at higher temps oil will lose some of its viscocity. Poorer quality oils can drop from 5w30 to 5w20 at those high temps. The lower the weight the thinner the oil.

The other advantage of synthetic is less volatility. When oil gets hot it can "burn off". Hence why vehicles have a PCV valve to catch those gasses. Synthetics have a higher thermal break down than conventional oil. High quality synthetics will not "burn off" as much as conventional oil.

So synthetics are not thinner than conventional oils and they don't slip past the seals in your vehicle easier. They will clean your engine better and once that dirt is gone there may be gaps left behind that oil can slip past. The good synthetic producers add the seal swelling additives to counter act this. The sooner you use good synthetic the better it is on your engine.

If you want the best oil out there start putting Amsoil in your vehicles. There attention to detail is not matched by any other oil manufacturer. They are also the only oil manufacturer that I know of that put a warranty on there product

[WPGQX4]

Oh and my QX4 has 175,000km on it and I added synthetic to it when I bought it with 167,000km. I'm still at the full mark almost 6 months later. Maybe the 3.3 is better at keeping oil that the 3.5. Doesn't the 3.5 have that issue with syphoning oil through the PCV valve?