jrrhd73must

Hiker,
I here what you are saying all the time. However, I am an engineer. I rebuild, remanufacture and upgrade Air Force air craft and helicopters. How many air planes (commercial included) change their oil on a specific mile or time interval? NONE! Not one. Even big diesel trucks on the road don't change their oil at specific intervals. In the flight community, where safety is paramount, we sample the oil to determine when to replace it. I have never changed the oil because it was bad in an aircraft, only because the engine or tranny was going bad. They use synthetic.

My why change oil at 3K, is because Amsoil will warranty your car for 25k miles or one year, against no extra wear tear, if you had changed the oil at 3k using dino oil. Amsoil is a full synthetic. I put Amsoil in my Harley and the bike ran 22 degrees cooler. I have been running Amsoil in my F250 for 22K miles. I have been sampling it every 5k to see how the oil is doing. The amsoil at 20k sampled better than dino oil at 2k. I have the samples to prove it.

Yes oil gets dirty, the filter is supposed to filter out the contaminents. A good synthetic will have enough detergents to run much longer than your dino oils. I service Harleys on the side, just by looking at the metal pick up on the plug I can tell you what oil was run in the bike. HD with 5-7K on the oil never have any metal shavings on the plug when Amsoil is run, however any other oil at 3k miles there are metal shavings. Note: not as many with Mobil 1. I tore apart an engine with 120k on Amsoil, there was little or no wear, in fact all of the tolerances were still within new car factory specs. No other engine have I seen in such great shape.

I know this sounds like a salesman, however My expereince with the oils over the last three years there is nothing that compares or comes close. My point in my signature is why waiste the time and effort changing your oil ever 3k miles if there is another way, in my opinion better. The only people that swear by the 3k change interval are the iol manufactures. Even Mobil 1 has started recommending exteneded change intervals.

lClutchl

I've been on a project with a major oil manufacturer. We had to do a lot of testing on oil durability. I can't talk details, but everything jrrhd73must says is true.

I run the dog-snot out of my cars and have since shifted from a standard 3k schedule to a 6k mile, 6month oil change using synthetic oils.

73Cleveland

This may have been touched on before but with running the oil with longer change intervals, which filter is best as lasting 5k+ miles?

Does anyone advocate changing the filter say at 5k and the oil at 10k ?

Soaring

A lot of tests have been done reagarding all the synthetics, and Amsoil and Redline are both at the top with Mobil 1 trailing. The only reason I would recommend Mobil 1 is for the convenience of buying it and the price. I personally use Redline and their filter. I change mine at 5-7K whether it needs it or not. I may be wasting money, but changing it at 3K is just a plain gross waste of money. Here are the typical advertistments, and tests for Mobil1 and royal purple to back up the claim that synthetics are far superior to dino oil, and that the change intervals are much greater. So, there should be absolutely no doubt in any thinking person's mind that not only are synthetics better for your engine, but that the oil change intervals are far greater than dino oil changes. As far as changing the oil and not the filter. Why? cost? That is not even good reasoning imo. http://www.mr2.com/ARTICLE/Mobil1.html
http://www.royalpurple.com/tech/whyrpi.html

73Cleveland

I agree it's cheap insurance to change oil whether synthetic or dino at reasonable intervals.

What I was wondering if changing the filter between oil changes may have any benifit? For example, say you were changing synthetic at 7k, would it be of any advantage to the engine to change the filter at 3.5k and also at 7k with the regular change? This way it would get a new quart of oil and a fresh filter that would trap more impurities in the oil.

jrrhd73must

Actually with Amsoil that is what they currently advocate to change your filter halfway at 6 months or 12,500 miles. I change my filter every 5k.

Soaring

I like to start fresh with each oil change, therefore I change the filter with each oil change. Yeah, I am probably wasting a few bux by doing it that way, but I just feel better that the entire oil change system is up to par all at once. I have never been an advocate of mixing old used oil with fresh oil.

Charlie1

My dad and I had great success with Mobil 1 with a couple of cars back in the 80s (running 8m or more on intervals...back then Mobil advertised 25m!). But I think I remember an issue with failure on seals...was that a myth? (didn't happen on my Datsun 4-banger or a couple of my dad's mopar 318s). Do the additives evaporate after 3m and that's the change interval issue?

Biggest advantage here in Minn for synthetic is cold-weather viscosity, we decided. January start-up's with glue-like oil for the first minute can't be good.

tylerdru

I dont trust the same oil in my engine for that long! dont you have to add oil every once in a while? I dont care what anyone says i will change my oil every 3-5000 miles. I dont care if amsoil has a warranty.

73Cleveland

I've never used a synthetic but have considered it. I always change my oil at no more than 3k. I don't drive it that far that often so I get a lot of moisture in my oil because it doesn't run long enough to get good and hot.

Since I don't run that many miles per year anyway, I change it every 6 months.