do I really need to change my oil?

I bought my '01 Ram Van with 14k on it 5 years ago, and it now has

21k, and I've only changed the once at around 17k. I'll probably do it again this spring. I'm also running Mobil1 synthetic. Hell I'd be changing the oil every 3 months and it might get only 200 miles on it if I went by the 3 month deal. :)

Oxygen and moisture are the only things that I would think would cause a problem, Nate. Oxygen is a problem at increased temperatures, which you would not normally get in a stored engine. Moisture could be a problem if you were in an area were barometric pressure and humidity changed a lot.

But if you warm up the car occasionally and drive it, I am with you...I think the "shelf life" would be long.

I'm not an expert but I drive so little now that I change oil annually at about 1000 miles and fully purge all brake fluid every 2 years as that's way cheaper than a rust failure (all my cars are 1965s).

I can afford it and choose not to worry over it. YMMV.

p.s. oil in our culture is not 'dumped'. It's recycled.

I think you are spot on. I have too many vehicles to put very many miles on most of them. I've gone to using Mobile 1 and changing oil every 12mo/12000 miles in them all. The lowest usage one may only get

2000 miles on it during the year and the highest mileage one gets about 12000. I just pick a day around the one year point and change the oil in them all and am set for another year.

Dang, an idea just hit me.. I ran across one of those toilet paper bypass filters on a junk yard car a couple years ago and almost took it "just in case" I ever found a need. You could take one of those and make a stationary recycling system in your garage and use the 2000 mile "dirty" oil and clean it up and use it for lawnmowers and such. It's really a shame to toss the "old" Mobile 1 every year when I suspect it's barely broken in even tough it looks dirty.

brake fluid, I'm not going to argue with you on that. That stuff is hygroscopic, and I've long been in opposition to those manufacturers who don't recommend periodic flushes. Which reminds me, I should check the manufacture date on my company heaver, it is an '08 model year. And the Porsche and Studebaker are probably almost due for another flush, seems like I just did it! (the truck just got a complete brake job, as in I literally replaced everything except the master cylinder, hard lines, and rear drums, a little over a month ago. Amazing how well an old vehicle can drive if you just make everything right. I am hoping, since I used good quality pads, that if I simply keep changing the fluid every couple years, I'll never have to touch those brakes again. I also painted the calipers and rotors with silver "caliper paint," because I'm anal retentive )

nate

This one, not sure if I want to bother with synthetic. I've replaced the pan gasket and lifter cover gaskets and also retorqued the valve cover, and it still is marking its territory. Once it warms up I'll crawl under there with a rag and some kerosene and shine up the underside of the engine and see if I can see where it's coming from, but if it's a rear main seal I probably will continue with the "check the oil every fill up" routine and not worry about it. It's at 140K miles right now...

I have thought about trying AutoRX in it just to see if the snake oil really works, but it'd take me so long to get the recommended cycle mileage on it...

nate

Acid formation. Condensation reacts with combusion by-products and forms organic acids. Using a higher grade oil won't do much about that because you still have the same engine blow-by.

This is one of the few cases where oil testing might actually be a good idea, since all you really need is a rough pH and conductivity test. Have the oil checked after a year and if it's still good, extend your change interval.

--scott

I put about 2K on my truck. I change it once a year.

If gasoline had no sulfur in it your argument would make a lot more sense. But the combustion products of real gasoline do produce sulfuric acid and some blowby always occurs. Further, while they do work to reduce it, there is still some oxides of nitrogen produced. I assume any blowby plus water makes some form of nitrogen acid. And while the oil itself may last forever, I doubt if the detergents do.

I'm changing oil on my Bonneville every six months. At almost 322,000 miles ireally isn't going to make much of a difference now......The car was only driven 4000 miles last year.

Mother's car might get two oil changes in a year as it moves aout

800-1000 miles a year (91Cadillac).

Buick oil is changed every 4,000 miles or there abouts.

harryface

91 Bonneville 320,999 05 Park Avenue 93,865

Lubricating oils have a neutralization equivalent, called the TBN or Total Base Number.. They can and do neutralize a certain amount of acidic components, including sulfurous and sulfuric acids,nitric acids, organic acids, etc.

If that neutralizing value is decreased or destroyed, that is a strong reason to change your oil. (But it is cheaper to change your oil than to diddle with an oil analysis).

Just letting good clean oil stand in an unused engine is not likely to contribute to any significant wear or corrosion over the shorter term. Now, if your block is full of DexCool, obviously that doesnt apply:-)

All of this is true,,,, but it is all designed to work when the oil is at operating temp and circulating in an engine. It isn't really designed to perform well when the oil sits cold doing nothing. The oil change recommendations are based on tests where the oil is spending a good bit of its time at operating temps circulating in an engine. The additives that hold soot in suspension or neutralize acids don't perform as well when the engine operating below normal (cold starts and warm-up) or not running at all. In general I would think a vehicle that isn't driven much should have pretty clean fresh oil whenever it is driven to keep it from deteriorating. A 30 year old car that has only 30kmiles on it often has quite a bit of wear if the oil isn't kept exceedingly fresh and clean throughout its life. And even with the oil kept very clean a little driven car like that will still have more ring and bearing wear than any car that is 2 years old with 30k miles (even when both cars have the same number of cold starts). Some part of that of course is the technology has improved in the last 30 years.

Another thing that you need to look at is how the miles accumulate. There is a big difference in someone who drives 2 miles to work in the morning and then 2 miles back in the evening 5 days a week for 50 weeks of the year and someone whose driving consists of an 85 mile trip once a month. they are both the same number of miles (about 1000) but the short trip guy probably would be better off changing oil more frequently.

-jim