I have never used synethic oil on my car. I use regular oil since it's from fossil. I change it regiliously every 3k miles. The interesting thought that since synethic is man made, does it needs to be changed more frequently or do they outlast 3k miles before it's time for the oil change. It seems like synethic are likely to get sludge build up if it were the case that you don't need to change it for....let say....5k. I've noticed in my other car, the Mercedes uses Mobil One, and when I open the oil cap, i can see the varnish and a smidge of sludge around the cap ring.

 

I'm sorry if this seems harsh, but if you take the time to look at the threads on your screen and read them you will find your answers. The next 3 threads are about this same subject. The oil analysis spreadsheet located in this same section has a huge amount of great information.

Short answer: With Amsoil you can go up to 17k or so on 1 oil change and 2-3 filter changes. With Mobil 1 you can go 8-10k or so with 2 filter changes. Oil analysis shows no varnish, sludge or anything of that nature happening in our cars.

 

synthetic=use Now Or Pay Later

 

Thanks for the info Virus, i appreicate that.

 

FanaticMadMax, when you said varnish and sludge around your oil cap. Can you please explain this thoroughly? It sounds like condensation may be a culprit. If water of any sort is getting into your oil, chances are you will have to change it more frequently.

 

Synthetic oil is going is not going to produce the sludge and varnish that a dino oil will because it is much cleaner and has less impurities even with a 7500 to 10000 mile interval.

If you are worried about sludge and varnish, take a look at auto rx.com.




What kind of iron and lead #s are yours UOAs (used oil analysis) showing in these extended drains? Have you seen the Amsoil thicken with these intervals pushing the oil out of grade to a 40 weight? I was unable to find your report on Bill's spreadsheet.

 

I did UOA's for quite some time, but when I moved this year they disappeared My wife Durango didn't experience the 0w-30 thickening. My Maxima however did experience thickening. It never reached a 40 weight oil, but to be honest I change mine every 10k with filter changes at the 5k mark with the Mobil 1 M1-105. Analysis showed I could go longer, but reading about the thickening and knowing that I do the D.C. rush hour thing for up to 4 hours daily I decided that 10k was my number. My wifes Durango would see 1 year intervals with a 6 month filter change. She didn't put many miles on it. We recently got rid of the Durango for a Nissan Titan CC LE. Kinda makes the Maxima's torque seem like a girly man

 

NOT true at all

Read..

http://forums.maxima.org/showthread.php?t=361671

 

If your valvetrain looks like this while it's running on dino oil, with your 3,000 mile oil changes, I really don't see a big need to swap to synthetics. Couldn't hurt of course. But not that needed.

 

Definately looks very clean in there. Synthetic helps the environment and saves you more money over time with extended drain intervals and gas mileage

 

I understand the rush hour traffic since I commute in Atlanta. I have started using a product called lube control in my synthetic oil (Castrol Syntec 0w-30 made in Germany) and fuel power in the tank at every fillup to get better results in my UOAs. I was skeptical at first about lc/fp but after seeing the iron and lead readings go down on many vehicles, I became a believer. I am running an interval of one year/10k miles with the same filter. The lc is supposed to control the thickening and oxidation. The fp can be run with 89 octane instead of premium but I alternate the BP Amoco Ultimate with no fp to keep the octane up. Unfortanely it will be November 2005 when I change the oil and get a UOA.

 

UOA 98 Max, 56K on the engine, 6-months (May thru Oct) 8500 mi on AMSOIL 0w-30, south Texas heat, zero oil consumption: Iron 6 ppm, lead 11 ppm, chromium 1, viscosity @ 100 deg C = 11.2 (range 9.3 to 12.5), 28 mpg avg.

 

That is an excellent UOA. The S2k 0w-30 could have gone twice that far with the use of lube control and fuel power. Although the Amsoil 0w-30 is one of the best oils on the market, it cannot absorb fuel the way it used to because the natural solvency of gasoline was removed by EPA mandates. On 10k+ runs, the insolubles go up and it can thicken out of grade.

In order to justify buying the premium 0w-30, it would need to be run up to 15k miles.

 

I change the oil every 6-mos regardless of mileage...4 quarts of oil at dealer cost isn't going to break me as the car is so reliable and efficient in other ways. I perform routine UOAs as I like to see how (little) the engine is wearing and to substantiate the extended drains.

 

talkinghorse,

Are you using the Amsoil SDF 20 filter?

 

No, I've been using the SDF-13 as that's what AMSOIL recommends for the engine. Some folks prefer the 20 as it is larger and slightly less expensive. The by-pass relief valve on the 20 is also set to a higher opening pressure...and I can make an arguement either way on that point. I've had good results with the 13 although it's physically small...