Fossil oil willnot fail to lubricate as long as it is clean. The main reason for regular oil change intervals is to replace dirtyoil and replace the additive package. A study by the University of IL several years ago showed this to be the case and fossil oil will lubricate as long as it is cleanand there are notmechanical issues that exsist already. The study also concluded that the best oil they found was "recycled" oil. Oil that has already been used in a vehicle and then cleaned and a new additive package put back in. There are impurities that cannot be refined out completely and the normal temp cycles tend to burn the impurities out. Keep in mind this study was done 10+ years ago and technology is farther ahead since then. In theory just replacing the filter with a good quality filter periodically can be just as effective as changing the oil at 3-7500 miles. When I first started a working at a dealership (Ford sorry)Ford recommended replacing the filter every 3-4K and the oilevery secondfilter change. I have seen engines where the oil has been changed every 3K (documented) and had tothe replace rod and main bearings and the inside looks like someone dumped in molasses, and some where the oil wasn't changed for 50K that still look clean.

Bottom line is I believe the real secret isn't if you change the oil at 3K or 50K make sure whatever you use is HIGH QUALITY oil/lubricants and filters. I don't think anyone spending 30G+ wants to abuse it with cheap materiels or parts. You get what you are willing to pay for.

 

I'm calling bull**** on the 160,000 miles. I've seen oil from an engine with 36,000 miles on the oil change and it was so sludged up it barely came out. It took quite some time to clean the oil pan too

 

i know all i run is castrol syntec and i dont think the change oil light has come on in my car in the last year but i change my oil about every 6k and the oil still runs out looking close to new slightly brown now i can say its probably not worn out at the point but i just can see going longer than that on my oil

 

I would prefer to go 10 to 15k, but I'm not sure about warranty impact. I use Mobil 1 (which rates about the same as Castrol Syntec), but may switch to Havoline synthetic since they rate as one of the best according to the Motor Oil Bible. I don't think there is any doubt synthetic is far superior to organic oil. 3k change is definitely a waste of money and oil. I guess it keeps the oil companies from going broke!

 

I use the extended life aswell, but I change it about every 8k miles with the filter. The my driver information display usually tells me to change my oil about 7-9k miles depending on how I've been driving, tells me I'm down to about 20% right now and it's been 4k I want to say since I've last changed it. I don't use On-Star so I couldn't tell you what they'd say.

 

I read an article in Car & Driver awhile back that talked about this. I don't remember the exact details but I remember it said that 3k used to be the standard for oil changes but with changes in technology in todays engines and oils that oil changes aren't needed nearly as often. I don't remember the exact numbers it gave but I believe it said somewhere in the 10k to 15k range. I wish I could find that article. I've been using the Durablend 50% synthetic and changing it every 6k but I may try switching to the extended life oil you mentioned.

 

I think you are talking about this.

http://www.caranddriver.com/features...olumn/(page)/1

 

35-Hundred Miles.
Oil and Filter.
Religiously.
You spend the money so you don't have to spend BIG Money and rebuild the Engaine, replace ring, seals ... Yada-yada!
It's longevity insurance.
Mobil-1

 

Yea I think that was the article Sir Monte, nice find!

 

My step dad has run Castrol GTX in his '91 Beretta since day 1. He now has like 485,000 miles on the original motor. NO WORK other than regular maintainence. He has replaced the transmission. Next time I go home I'll take a picture of the odometer for you skeptics out there.