Bananax

iTrader: (3)

Maybe.... My wife's car, E320, gets oil change at 12,500 miles and that's recommended by dealer.
I guess I change oil too often.

Anomaly

iTrader: (7)

I'm surprised at some of the less than 3k oil changes myself...

Anyways, whilst searching the net I found a site that did Blackstone studies on both Mobil 1 5w30 and Amsoil 5w30 for a Chevy Camaro (LS1):
http://neptune.spacebears.com/cars/s.../oil-life.html

Still reading all the 1k mile reports but pretty interesting so far - especially the oil longevity reports.

Z_Driver

iTrader: (3)

Regular oil 3-4K: Synthetic 5K. Check oil level at every other gas fill up.

I like to keep the oil nice and clean.

Dang that Nissan Z oil stick ....

derek173

iTrader: (3)

WOW!!! .... any synthetic will last 7500 miles easily, most are good past 10k.

STOP WASTING YOUR MONEY!

I suggest you guys give castol 0w-30 made in Germany a try (sold only autozone) . Its a thick synthetic oil, that has good results, I have seen used oil analysis done on this oil in an '04 g35. The oil was run to 7400 miles the analysis was done by blackstone labs. It showed little to no engine wear, very low particle count. The oil can easily be run to 10k+

Mobile one now sells a synthetic oil that is guaranteed to 15k. I know two people running this oil right now an 04 Silverado and a 1998 Civic DX with no problems at all.

RobertH

iTrader: (3)

i hate the z oil stick. i changed my regular oil every 3k, but now that im using synthetic(royal purple) i change every 5k(when i changed my oil last, it still looked pretty clean).

SilverII

5k

Silkk

iTrader: (11)

I try to do it every 3000, but sometimes it gets to 3500 if I'm working out of town or whatnot.

I'd never let it go 5000-10000.

dutchboy350Z

iTrader: (5)

There have been plenty of studies that show there's no real advantage in changing your oil @ 3k instead of 5k. Especially when synthetic oil is involved.

when it comes to:

Sludge Deposits
Varnish Deposits
Rust Deposits
Cam + Lifter Wear

Studies have shown @ 3k, 6k, 12k there are very slight differences. And these test were run on NYC taxi cabs.

http://www.worldsbestoil.ca/amsoil_t...-10w40-oil.php

Gralark

every 5k with my mobil1 and k&n gold filter.
some key notes from that mobil1 study:

"Engine wear actually decreases as oil ages. This has also been substantiated in testing conducted by Ford Motor Co. and ConocoPhillips, and reported in SAE Technical Paper 2003-01-3119. What this means is that compulsive oil changers are actually causing more engine wear than the people who let their engine's oil get some age on it."

"One thing we're pretty sure about though: 3,000-mile intervals is a huge waste of resources."

daveZ insanity

iTrader: (4)

That's a bit harsh - but in my opinion it's right. Very few of you have ever measured your bearings, rings and valve guides for wear, done a leak-down test, or sent your oil out for analysis (a cheap and effective way to monitor engine wear) - but I've done all those things for decades so I could get my family and my trailer (with a race car and literally a ton of spares and tools) to the track, race and get it all back home again. I maintain my street vehicles and build / maintain my race cars - so I've seen and measured hundreds of bearings, rings, cylinder walls, crank journals etc.

I've sacrificed a lot of dinosaur flesh over the years. My new Z is street vehicle #44 for me since 1966, if I count correctly. I've towed multiple race cars over 200k to tracks from West Palm Beach to Shannonville (Ontario) and in between with a Pathfinder, a Bronco, a Suburban, a Chevy P/U, and a Subaru wagon (once in a pinch). Before I could afford a trailer, I drove the cars to the track, changed oil there, ran, changed it again, and drove home.

From '66-72, I changed the oil every 1000 mi in my first cars, which were a '58 XK-150 ($300), a '57 Porsche ($400 - it was actually $100 less of a wreck than the Jag!), then my first new car - a 1967 Mini Cooper 1275S, in which I drove SCCA solo events. As oil got more expensive near the end of 1973, I had to find a way to save some money (I got married in '72, so I had 2 street cars plus my toys to maintain). I started used Oberg filters so I could see what was in the oil (after a few years of cutting spin-on filters open to see what was circulating). I did regular leak-down checks, sent some oil out for analysis, and opened up a few to measure the internals. And I reached the same conclusion by 1980 or so that manufacturers are now promoting - e.g. the oil change indicator on my '03 Mini came on at about 12,500 regularly over the last 3 years.

Like me, virtually none of you has ever had an oil-related engine failure in a street motor - this fear is basically groundless. So my recs are: for normal driving up to 7500/yr, annual changes; over 7500/yr, every 7500-10k. If a lot of your driving is for less than 15 minutes, especially in cold climates, your oil doesn't get up to operating temperature so whatever little moisture condenses into the sump won't vaporize again (an oil temp gauge is useful here). Enough of this can cause oil to lose lubricity over time, so change it every 3 to 5k (twice a year if <7500/yr) if you only drive short distances. I only use synthetic and I found no difference by brand in the race cars - so I buy whatever Pep Boys has on sale.

Change your air filter annually (more often if you live or drive in dusty places). The fine stuff that gets into the engine through the intake is what wears your internals. A dirty filter will still filter - you need to replace it because it gets little rips in it that let dirt in.

Act of God

Well put, I never bought into the 3,000 or less hype. Hell, when I was a kid my dad had a Subaru wagon that he never changed the oil on. He would only add if it was low. That thing lasted forever (not that I condone never changing oil).

I think 5,000 miles is a pretty conservative interval for running synthetic. You could probably safely go to 7,500

MustGoFastR

iTrader: (13)

+1 on that (sort of). I had my Mobil1 analyzed by Blackstone at 5k and they said it could easily go longer. I change mine every 5k, though; I could go longer and keep testing to see the perfect interval, but testing the oil costs almost as much as buying new oil, so I just change it. I also don't put very many miles per year on (maybe 8K), so change it at 5k to keep the moisture absorbtion down. Testing will tell you about moisture content as well. Bottom line is that you can likely go long periods if you test your oil periodically and know where you're at (every engine can be different due to conditions, driving habits, etc). If you don't test your oil, it's better to err on the side of caution, but you can do 5k at a minimun.

HyperSprite

iTrader: (6)

Between the 6 and 7k

Chris

dutchboy350Z

iTrader: (5)

+1
Thanks for spreading the knowledge. If only this site could have more useful threads such as this one.

Z_Driver

iTrader: (3)

I agree with the fact that 5K might be a bit premature on an syn oil change. Especially, if you drive that 5K in three months.

Let me point out however, that six months is another deciding factor for me and I just about hit 5K at six months. If my oil is in the crankcase for over six months or so I try to get it out of there weather of not the car got to the 5k mark or not. You see, it's the acids you want to get out of there. They breakdown the oil as well.

just my .02

03performz

iTrader: (8)

I've been using Mobil 1 ever since 10K mi. as per Nissan. I change it every 3k and it looks as if it could use it. God, I love the smell of Mobil 1. Am I alone on this?

Silkk

iTrader: (11)

Well, since I already stated my oil use habits I guess I will state, for the record, that I do throw out day old milk...

Alberto

iTrader: (14)

NA I changed every 3000-3500 miles. Turbo I changed it at 2000 mile intervals....

daveZ insanity

iTrader: (4)

The color means nothing. A mayonnaise-like blob (even a tiny one) means moisture. You can check the dipstick for what looks like a crust of tiny dried bubbles - that also means water (actually it's antifreeze). I know, I know - oil is lighter than water - but if antifreeze gets in through a crack or a blown head gasket and hits the hot dipstick, it crusts. If there's solid stuff in the oil, you have to find out what it is and fix whatever's wrong. There shouldn't be any particulate content at all.

There are many other things you can diagnose by looking at and smelling the oil. But the things you'll find there are all wear or breakage items, and you probably won't find any of them in a late-model Z.

derek173

iTrader: (3)

Very true Mobile 1 turns black after a few miles, doesnt mean anything.... dont waste your money, at teh very least the oil will be good for 7500miles.

Mobile 1 5000 mile oil = Dino
M1 7500 mile oil = Dino + synthetic
m1 15000 mile oil = Full sysnthetic

I run German Castrol Syntec 0w-30 to 7500