How long can you wait between oil changes when using synthetic oil? Dodge and Instant Oil Change says 6 months or 6000 miles, but I seem to remember always hearing that you could wait 10,000+ miles with synthetic. It seems to me that buying synthetic at 2X the price accomplishes nothing when it only doubles the amount of time you wait between changes.

Andy

Lets see Mobil 1 now has 15,000 mile Oil .. or 5,000 or 7,500 .. Which always makes me think ? why would I buy 5000 mile when they have a 15,000 mile...??? But thats another debate I guess..


The value of syn oil would be it better lubricates even IF you change it the same as Dyno Oil ...

The Thing with OIL CHANGES is The OIL will OUT LAST THE FILTER even with Dyno OIL.. Me I would have No Probs running Syn Oil 10,000 miles .. The Oil Filter... Wellllllllllllllllll.


I run the Mobil One Pure syn in all my cars .. I plan to drive them till I am gone or till the car is gone whichever comes 1st..I change them around 7,500 because I dont trust the filter and yes I should just change the filter and go another 4000 BUT I dont ..

except the Chevelle in which I run Valvoline Racing 20/50 ..I change it about once a year ..Again ..Just because..NO scientific reason ...

... It seems to me that buying synthetic at 2X the price accomplishes nothing when it only doubles the amount of time you wait between changes.

Andy

Seems to me it saves you the aggravation of changing the oil so often. Same price, actually less only one filter, at the end and you only had to change it once, not twice.

doesnt synthetic make the engine run A LOT better though? and protect it more?
i was planning on doing 10-40 in my 350 for the summer with that lucas oil stuff that keeps from dry starts and all that good stuff... of course if synthetic is better im going to call my friend up and get amsoil synthetic..

Dont run the lucas oil additive it makes the oil foam, unless your engine is very old and is very worn out. I wouldnt use it or if you have a high performance engine dont use it cause the higher the rpms the more the oil will foam.

oh wow! Thanks for that comment! Looks like that is out of the picture! It looked good at the store, they had a little "gear" wheel thing setup, and one was filled with regular oil, and the other one had the additive... the additive did stay on the gears a lot more... but in an engine if its going to foam, that really isnt good at all.. i would rather have a dry start than a wet start with a dry run lol

Andy,
I have been using Mobil 1 in everything I own for about 15 years now, maybe longer. Here is a pictue of the valve train on my 84 S-10 shop truck's 2.8. It has about 260K miles on it now and this picture was taken last fall when one of the valve covers started leaking. This was the first time anything had been done to this engine other than tuneups and Mobil 1 since new .. changed about every 5-6 K miles. The pic of the valve cover was after I put it in the parts washer and rinsed it off for about 2 minutes just to get the dirt off the outside. If this dont make a believer out of you ......

If you guys are using syntetic and changing it between 5k and 7.5k isn't that kind of wasting it? You can run non synthetic oil 7.5k. Just look in your vehicle specs. 3k oil changes are just something made up by oil companies to sell more oil,that's a fact. I recall a study done several years ago on 20 new york city cabs with GM 350 engines. Half the cars had the oil changed at 3k intervals. The other half had the oil changed at 7.5k intervals. After 65,000 miles( this was done since they were brand new) all the engines were removed and all wearable components were measured with a micrometer. There was no difference in wear between the two groups and this was done on New York city cabs and I'm sure they weren't babied

If I remember the test correctly they used a number of different motor oils, all rated 5W-30. I thought they chancged to oil at 3K, 6K, and they even went to 12K on some of the engines.
The results they found were that it didn't matter what brand oil you used-as long as it had the API star on it you could use the least expensive oil. They did mention that the engines were almost never turned off, so the test didn't reflect any cold starting protection.

If you are planning on running the oil for an extended period you should have a UOA done. This is a Used Oil Analysis and they check for metals and impurities in the oil, as well as the overall life left. I think you tell them how many miles are on the oil and they can tell you how long you could go until the oil needs to be changed.

Dont run the lucas oil additive it makes the oil foam, unless your engine is very old and is very worn out. I wouldnt use it or if you have a high performance engine dont use it cause the higher the rpms the more the oil will foam.

what is the basis of your statement about foaming with Lucas, not my personal experience? how does a thickening agent cause foaming?
thanx

Well, if you go by AMSOIL they claim their synthetic oil only needs to be changed every 25,000 miles or once a year.

I am not a believer in the extended oil change periods advertised with synthetic oils. I believe synthetics provide better lubrication and don't breakdown as soon as regular oil, but I am not sure any oil is going to keep your motor clean that long. Oil changes are relatively cheap and easy, and for the peace of mind I like to stick with recommended oil change intervals and keep fresh oil in my cars.

I use Castrol Syntec in my daily driver and change it every 5,000 miles as recommended by VW. But that's only 3 oil changes a year and I use the synthetic for the extra protection because I want this car to last as long as possible (will synthetic oil help, who knows).

For my old cars I change the oil twice a year and use regular oil. Synthetic isn't worth it for them because they don't see the miles and I believe fresh regular oil is better than keeping old synthetic sitting in them.

what is the basis of your statement about foaming with Lucas, what he asked :confused:

what is the basis of your statement about foaming with Lucas, not my personal experience? how does a thickening agent cause foaming?
thanx

I think this is the often referenced test....

http://www.bobistheoilguy.com/images/lucas/lucas.htm

Lots of info from the home page on down.

I use Amsoil in all of my vehicles. I use the Dual filter system on my box van for work. I usually change the oil once a year or when it gets dirty. Amsoil dealers can take a sample of your oil and send it in to the manufacturer for analysis. It will tell you if there are any pollutants in it such as antifreeze, if your vehicle is running rich (traces of fuel in your oil). It only cost 12 dollars. I do that once every 3 months. It ends up being between 10-13k miles between changes.

Go to http://neptune.spacebears.com/cars/stories/oil-life.html for an ongoing documented study of sythetic oil life. Personally I was having a problem with low oil pressure and funny noises in my S-10. I changed to Syntec synthetic and a Mobile 1 filter and the problems went away. Matter of fact the oil pressure is higher now than it has ever been. And I'm running the oil to 10,000 miles.

I run fully synthetic in my Chevelle, I just change it once a year every spring, probably only about 1-2 thousand miles at most on the oil each year.

It really depends on the driving environment, fully synthetic oil doesn't break down like dino does over time, so I'd have no doubts running it for over 10,000 miles unless it's a dirty environment, since dirt/debris in the oil is really the main reason to change the oil and filter.

blm,
You are probably correct and I have actually been stretching my intervals longer and longer. My S-10 gets a lot of short trips, I only live about 5 miles from the shop, so I probably wont go much more than 6k with it, but my Tahoe has probably been about 8k right now. 99% of it's mileage is highway, so it is nowhere near as hard on the oil. I was planning on changing it in the next few weeks so I will see how it looks. Personally, I think that is a good indication too. If the oil still looks clean, it probably has a fair amount of life left.
Another real big factor is the type of car and fuel system. Modern engines with electronic fuel management do not contaminate the oil with extra fuel anywhere near as much as a "Hot Rod" with a rich running Holley on it.

I use Mobil 1 in my Monte Carlo SS on BillK's recommendation from day one with a fresh engine. I change it once a year, the car only gets about 3,000 miles a year on it. When I do take it out, it gets a pretty good drive, like 45 minutes to and from work. I use Mobil 1 in my 2002 1500HD too, since the first oil change and all is fine with both engines.