I bought a case of that 5k oil from walmart for around 23 bucks its great oil Ive been really happy with it and the motor responded well to it. I went with the 5k oil because I get to anxious going any longer than 5k on an oil in an engine that I like to beat the livin hell out of

 

I would still get the full synthetic and change it early.

 

Like Greggo said..........
Read the bottles
The oils are not syn
only Mobil 1 is
the rest are just a Mobil oil.......
I found them at Auto Zone - I wasnt impressed
M1 went into the cart

 

I manage a fleet of vehicles. Our fleet management center has over 8000 vehicles and we go 7500 miles on standard oil.

Never had a breakdown due to oil. I personally go 3K miles, but management says, nope 7.5K. We do the bare minumum to keep the warranty and the standard for manafactures is 7.5K. At least thats what they have told me.

I have actually seen one agency go 24K with no oil change. Im curious to see how these engines must look inside. Can you say SLUDGE!

 

15000 miles on full synthetic is perfectly acceptable for "typical" vehicles. You must use either a premium filter as well, or change the filter every 5000 or so miles. I would never run 15,000 miles on oil in my engine simply due to the fact that it revs higher than "typical" and that it barely gets driven except to the track. On my wife's car, I run mobil 1 for 15000 miles. I change the filter every 5000 and top it off. We (my family and I) have been running our cars like this for ten years, and never had a lick of trouble.

 

I have been using M1 since 1990 in every vehicle I have owned and I usually go 10-12k before changing. I used to do the filter change/top off thing, but that is a waste if you are talking about an engine that is sealed up well. For example, my Nissan beater car has 11k on the oil right now. It is still full and is kinda medium brown in color.

If an engines piston rings aren't in the best of shape allowing the byproducts of combustion to get into the crankcase then you would need to change the oil sooner. I'm not saying that you can go by how dirty the oil looks, but the fact is that the main determining factor of how long you can go between changes on a synthetic oil is how dirty it gets. Synthetic oil doesn't break down and change chemical properties like petroleum based oil does.

 

I personally am going to stick to Regular Mobil 1 and ill change it at my normal intervals. I dont know about the 5k 7.5k and 15k. I am not crazy about the sound of that, 15k is a long time to go without changing oil.

 

Here is a link that was sent to me by a friend. An interesting debate but didn't change my mind on oil change intervals.

http://cadillacforums.com/forums/sho...3&page=1&pp=20

 

My brother is a plolymer chemist (nice huh) and he told me that conventional oil doesn't break down for tens of thousands of miles. The additives break down and the oil becomes dirty, but that takes a long time for that to become a factor.

With that being said I say change the oil at regular intervals. I would never buy those new Mobil oils. i use regular valvoline 5w30. Don't be too lazy or cheap to change your oil when you should.

 

I have been using the GM Oil Monitor System and running Amsoil 5w30 right now . The first run after changing to synthetic Asmoil 10W30 was 9300 miles. I had the oil analysed and it was in great shape and could have gone a lot farther. I will see what it is like after the next change which will not be quite as far. If you do go for extended drain periods then oil analysis can be very beneficial.