Oil life

[Franklin]

I keep hearing that oil should be changed every so many hours/miles or so many months, which ever comes first. To me that sounds like the oil companies are just trying to sell more oil. Oil is already very very very old, how is it that it's sitting in the bottom of an oil pan for a year going to make it any less effective? We aren't talking about something that rots away like food. Can somebody explain how it looses that viscosity in time that I hear so much about?

 

[Don]

contaminants

As the engine runs, it produces acids further contaminated by combustion byproducts which, depending upon the efficacy of the rings, also enter the oil. It isn't just mfg propaganda. I believe the conventional wisdom is to change the oil and filter at least once a season, preferably in the fall prior to hibernation in the northern climate or in your case, once a year minimally.Don

 

[Karl]

Oil

Oil does degrade but most of all it gets contaminated by combustion by-products such as...water, carbons, rust, ect. It's required to lubricate and cool your engine as well as protect against internal rust. Kind of like food, it's fortified and changed in chemical structure and not even close to the million year old stuff found in the ground. If you don't use your boat a lot change it once a year or twice if you use it more.

 

[KennyH]

additives get used up

The additives get used up just just being on parts and in the sump. The additive to slow rust would get used up first on a boat. Once a year change insures new additives to keep the rust away. If you use it often about 100 hours is a good change interval.

 

[Franklin]

details?

"The additives get used up just just being on parts and in the sump."How?

 

[Ken Prichard]

All The Same

All oil is the same. It makes no difference which brand or what quality you buy. It's the additives that make them different and it's the additives that break down by use and by time. The "oil" that is millions of years old will last forever. But if you want it to work you have to change it.

 

[Timbo3]

Oil is your engine's life blood

That's what my grandfather used to say. . . Change your oil regularly and your engine will thank you for it - and that Oldsmobile really did in engine longevity. Actually different brands of oil use different quality bases then add an additive package. The cleanest bases come from Valvoline and Castrol. Of all the different additives, I think the most important ones for us are anti-corrosive and anti-scuff. Anti-corrosive additives stay on the engine parts after the oil drains off.Deisels are very dirty, so your beautiful clean oil will get black very quickly. To help keep your oil and your engine in top condition, run your engine regularly up to operating temp for 20 minutes to get rid of moisture in the oil and the engine. Regardless, yes, you should change your oil regularly. What came from the ground has been distilled into a multitude of products and what you have in your engine is nowhere near how it started out.

 

[Baysailor2]

Oil contaminants

As has been said, oil doesn't wear out, it just gets dirty. It's this "dirtyness" that is the cause for engine wear. Changing the filter mid season will help keep the oil cleaner, but not aleviate the need to change it at season end. Changing it is especially important at the end of the season, with a sump full of "dirty" oil. The main reason to change it is that these contaminants become quite acidic over time and will begin to eat at your bearing surfaces if you leave the dirty oil in the engine for an extended period. Gas, diesel, it doesn't matter--the same thing happens. The oil may drain down, but the residue remains on all those nice micro-machined surfaces, which won't stay smooth if not flushed with a shot of fresh oil before a long winter's nap.

 

[Fred Ficarra]

I think this is one of our great American

subjects. Anything having to do with the internal combustion engine is pure Americana. Franklin, one of our cliché's is 'oil is the cheapest thing you will ever put in your car/boat/whatever, just change it.' Now with that said, here's one for ya. Computers! Our new Duramax Diesel truck monitors the oil life with the on-board computer. The truck is six weeks old now but the computer is projecting the oil life out to 10,000 miles! On a diesel! Of course the operating conditions this time of year are perfect and so is the way I drive. (only longer trips) But still, 10,000 miles! The owners manual tells you to change it at the end of a year anyway if the computer doesn't tell you to. Wow.

 

[Franklin]

yeah...but...

I've read in many places with cars that it should be 3,000 miles OR 3 months, which ever comes first. With that thought, I could change the oil, drive down to the part store and drop off the old oil, come back home, sleep for 3 months, wake up and it's time to change the oil again.I agree with the statement that changing oil is cheap compared to the replacement cost of an engine. I just wanted to know if there was an facts behind the 3 months statement or even a year on a boat. Same thing...if I changed the oil on my boat, ran the engine 20 minutes, then came back in 12 months, would the oil need to be replaced? Not that I would ever do that, but just curious.

 

[Fred Ficarra]

Franklin, that 3 month schedule is also very

American. For the purpose of making MONEY. And it's complete and total BS. As George Carlin would say. I keep my hotrod in a insulated garage year-round. When not being used the oil stays perfect for as long as I keep the car parked. (4 years once) Then there's my camper generator. It runs on propane. The last time I changed the oil was six years ago. Still looks like new. And my home backup generator, let's see,,,two years now. I run Mobil 1 in it.  This is coming from a guy that used to change the oil in his big block 69 Camaro when it was new every thousand miles. The oil was still golden. Haw! When the engine broke at 75K miles and I put a bigger one in it, the cylinder walls still had the original honing marks in it. In fact, it looked like it had never been started. And that engine used one quart of oil every 500 miles like clockwork. The rings never seated. Now don't anybody start yelling at me saying that I need to send my oil to a lab for testing to be sure it's clean. I know that you can't always tell by looking but I know the conditions that I store my stuff. I never put my horse away wet.