i have a friend that runs his car 12,500 miles on mobil 1 before changing it.
he said that his mechanic said that he could run it that long without changing it.
i run my car on mobil 1 also, but change it about every 3,500- 4,000 miles.
has anyone ever heard of such a thing?
i can't imagine going that long without a change.
how many miles do you put on your oil?

of course you CAN run that long on the same oil, and I would still change the oil when it is reccomended... it's not like your engine will just suddenly go boom... its just that the protective qualities of the oil get dimished after it has been used for so long and therefor it the detergents and anti rust agents aren't doing their job as much......

also fine particals also build up in the oil.

oh and another thing.. if you are going to spend money on an engine/car why put that money at risk by skimping on oil and regular matainence?

Protect your investment

I don't think anyone can dispute over changing your oil could at worst be good,but I run mine for 12000,but I change the filter every 3000 and top it off,this by the way is my stock vehicle,pcv,etc included,and not some cheezy filter either. Its super clean inside and has over 100,000 miles so.......maybe its not so bad?Synthetic doesn't burn and break down near as bad.

I suppose there are 2 ways to look at this. Extending engine life and extending oil change intervals. Personally I change ever 6000 km (x .6 for miles). I do this to extended the life of the engine. This is in my 93 Pathfinder with 190,000 km). I my Beaumont I change the oil ever 3000 km or so. I know it over kill but its also an expensive engine. In the trucking industry, running mineral oil, I run most trucks to 40,000 km and do oil samples. All come back with high soot and very little metal so this is a good change interval and I would not be comfortable extending it. My point here is if you are running extended intervals with synthetic oil, get oil samples done when you change the filter to make sure you are not over extending the oil. Synthetic oil, as well as the engine bearings and internal engine parts, still has to deal with contamination and dirt which can effect the life of an engine. Also, it depends on the driving. Here in Regina everything is within 10-20 min from where ever you happen to be, so engines don't get up to operation temps long enough in the summer let alone let alone in the winter when it -30 out. This results in moisture and contaminants in the crank case which wil effect the quality and life of an oil, even synthetic. I've seen engines seize up because of water in the crank case and pcv's freeze up and blow oil all over the place. Sorry about the length of this but there are still a few things to consider even when using synthetic oil so make sure you do your homework. By the way, I only use synthetic oil unless I'm braking in a new engine.

You can run longer between changes with GOOD synthetic oil such as Amsoil or Mobil 1.

Rifraf hit the nail on the head and does it the right way. Change the filter regularly and top off the oil.

Using a top quality filter is a must if you want to run extended periods between oil changes.

I know an Amsoil dealer and he only changes the oil in his cars once a year PERIOD. He doesn't put many miles on though (I would guess less than 10,000).

With dyno oil it is recommended to change every 3000 miles with synthetic 5000 miles is not problem at all. I would not go 12,500 miles without changing the filter and topping off regularly (every 3-5K).

Many years ago a friend of mine talked to one of the engineers who helped develop Mobil-1. He said the guys who developed it did the same thing with their own personal cars (after breaking in with dino oil) that Rifraf does. His '85 Tercel was run on Castrol GTX until Mobil-1 became routinely available, then Mobil-1 from then on. It has around 200,000 miles on it and only started using oil between "changes" when the front seal started leaking last year.

When Mobil 1 came out around 1975, they use to recommend 15,000 between oil changes! It's important to note that in 1975, GM use to recommend 10,000 between oil changes with mineral oil! As far as GM saying 10,000 was due to the fact that it was the first year that cars had catalytic converters and ran on unleaded gas. The simple fact of removing lead from the gas greatly decrease oil contamination and also significantly reduced cylinder wall wear. This was found out in the taxi industry

A few years ago Consumers Uninon did a big oil test using cheap and expensive oil. As their test fleat, they used a NYC taxi company using 4.3 Impalas. It was a very controled test. All enginges were rebuilt by one company. Each engine had it's own record with wieghts and measurements of all parts. In addition, the roller cams were removed and flat tappet cams put in to add wear. The test fleet was quite large and had vehicles using cheap oil, expensive oil and extended oil changes. What did they find? Interesting, no difference between cheap and expensive oil as far as performance OR engine wear! The taxis that ran extended oil changes only showed minor increases in wear or insignificant changes

I had used Mobil 1 on a car I had in the early 80's it had about 20,000 miles on it at the time and used a quart about 5,000 miles. A couple of thousand miles after using Mobil 1, I was using a quart of $5 oil every 600 miles. The Mobil 1 destroyed the valve guide seals and the car would smoke. Went back to mineral after having the seals replaced.

Rifraf hit the nail on the head and brought up the most important point, changing the filter!

If your friend is changing the filter at the half way point (with a quality high efficiency filter aka: Amsoil or Mobil 1) and topping off with Mobil 1, it is perfectly acceptable to go 12,000 miles or more with Mobil 1. You on the other hand are wasting money changing it every 2,000 or 3,000 miles. I use Mobil 1 and Mobil 1 filters and I go 7,000 miles between changes.

The key to using synthetic is to also use a quality high efficiency spun synthetic filter. Fram is not on this list, I don't care what their advertising hype says. every independent oil filter test i have seen consistently rate Fram at the bottom of the heap.

Vince

i don't see too many racers out there circle track for instance that don't change there oil after every race. they cant be going over 3000 miles and they change there oil. i have a sbc 350 and i use Mobile 1 and a wix filter and every 3000 miles or sooner depending on how i run my car i change the oil. no point in cheaping out on and oil change. and taking the chance i saw on a 67 t bird that had from the factory to change the oil every 6000 miles that was in 67 when lead was still a factor

One mistake people make with synthetic oil is to switch to it in a high mileage vehicle. This can sometimes result in an oil leak. This leak is not CAUSED by the synthetic oil. It is caused by the already worn seals.

I have seen reduced wear first hand by switching to synthetic oil. I have been sold every since.

The reason race cars change their oil so often is the oil is put through very extreme torture (high heat, extended high RPMs). There is no need on a street car to change the oil at 2,000 miles (IMO).

I use Mobil 1 and change it twice a year regardless of mileage. I don't use it because of the possible extended change interval but instead I use it because of the better thermal protection it offers and the better flow at cold temperatures.

I believe in changing it more often because just changing the filter doesn't remove fuel residue, moisture, acids, etc.

__________________
Ya cain't fix stoopid, but ya kin TAX it!

Tom,
I agree with what you said but, if the oil tempature is gettig the level it should don't you think the moisture and fuel should be burned out of the oil? No arguing the point just trying to get your take on it. I have been taught that by running the engine at the correct operating tempature you will reduce the amout of contaminants in the oil.

Now if you are talking about a car that is used a lot for short trips and very rarely get run for extended periods of time, I think the contaminants would build up more. Does that make sense?


Every six months sounds like a good interval to me and that is about what I do.

personally, I change the oil in my vehicles regardless of year every 2500 miles. Yuo should follow the owner's manual of your car though. The oil companies do a lot of testing but you have to remember that they can't check the results on every car. Ultimately, what causes oil failures are the additives being "used up" in the oil. When that happens, the oil can no longer handle all of the acids, water, dirt, sludge and such. Now, I believe that you can get away with just changing the filter at 3000 miles or so with synthetics, but you can't put the additives back in. So, what you have is after 6000 miles or so an oil that can potentially lubricate, but can no longer take care of all the requirements your engine has to stay healthy. I appologize if I sound preachy. I used to work for an oil analysis lab that made designer lubricants. Oh, and if you switch to synthetic, find out from the manufacturer of the vehicle is the gaskets can handle it. The reason the leaks form is because the addidtives in the newer oil may free up sludge holding the old gaskets together. Hey, good luck. I hope this helps. I apoogize again about being a know-it-all...just trying to help.

I live where it's cold much of the year so I don't get to heat up the engine up to operating temperature like I would want to. The short trip scenario also applies to me. I could probably do just fine with mineral oil, but I see so little wear with the synthetic I just gotta use it!~

__________________
Ya cain't fix stoopid, but ya kin TAX it!

Tom,
That makes perfect sense since you are in a very cold climate. I was just curious on your thoughts.