Miles or Months?
I've always changed my oil every 3 months regardless of miles 'cause I feel dirty oil sitting in the pan collecting dirt and moisture causes more problems than high milage unless you operate under severe conditions.
Any thoughts?

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99 XLT 5.4L Regular Cab 4x2 120" Wheelbase 4 wheel disc brakes/ABS 5 star larait style wheels Toreador Red/Silver 3.55 gears 255/70/16 OWL Delta toolbox, Ventshades, Bugflector, Bullrings, Donnelly compass mirror, 2" Rear drop.
Eclipse 5340 cd player
Memphis ARCS50 component speakers w/tweeters mounted flush in the door panels (excellent sound)powered by a Sherwood 35x2 RMS amp
Jensen 50x2 RMS for the 2 Audiobahn AWC10 subs
regcab54@sc.rr.com

 

Usually it starts by hanging out with the wrong crowd, then it becomes withdrawn and moody. Watch for signs of alcohol and drug abuse.
Oil - I honestly don't know, I change mine every 3500 miles (Mobil 1 5W30) whether it needs it or not.

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99 F150 XLT Silver 2WD S/C 4.2 5-speed, Pioneer DEH P4000, Superchip, Flowmaster muffler // Rear door switch guards - check them out at http://www.geocities.com/motorcity/show/5031

[This message has been edited by Darin (edited 01-02-2000).]

 

In most cases oil becomes dirty long before it goes bad. As far as oil going bad, I don't believe the oil itself actually goes bad. Most automotive uses don't expose oil to enough extreme heat to cause the oil itself to go bad, it is the additives, and the all important viscoscity modifiers (which are present in most multi-grade oils) that loose their ability to do the job they are meant to do.
Synthetic oil will last much longer than regular oil, but it still gets dirty.

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Michael
99f150@pickupman.com
mkrieger@mailcity.com
99 F-150 XLT Supercab, 4x2, Bright Red/Harvest Gold, 4.2L, Automatic, 3.55LS, 255/70R16 Goodyears, Captains Chairs, Keyless Entry, CD Changer, Tow Package

Accessories: SuperChip, Donnelly Compass Mirror, Lariat Wheelwell Moldings and Bumper Cap, Ford Splash Guards, Bug Shield, Bed Mat, WeatherTech Deflectors, Mobil1 Synthetic Oil

Modifications: Painted Tailgate Handle, A/C on/off switch

 

Both mileage and months are just as important. The oil builds acids and collects condensation, all of which leads to oil breakdown. Driving and sitting shut down your oil is building up these. In my opinion, mileage would be the greater wear on an oil due to the combustion process and heat. 3 months or 3,000 miles for me, although I am considering AmSoil and their 25,000 mile oil change.

Another note, my dad used to change his oil every 2-3,000 miles, which was evey six months. At 80,000 miles his engine was clean as a rebuild.(79 Bronco w/400M)

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1997 F-150, 4.6, automatic, Dark Toreador Red, Supercab, Flareside, 4X4 Off-Road, Towing Package, Ford hvy dty rubber floor mats, Chrome Grizzly Wrap Around Push Bar with 2 KC 100w Daylighters, Ventshades, Ford bedliner, cab and bed professionally undercoated, Code Alarm Sure Start RVS remote starter, Ford alarm, Realistic CB with Wilson Little Wil antenna and Astatic power mic, ported MAF sensor, and Lots of TLC!! (Besides being an F-150 nut, I am a Ford auto technician.)

 

In conventional oil, the breakdown process starts almost immediatly, because it contains by-products that cannot be refined out. Some contaminants include. Tar, Wax, Oxygen, Varnish, etc... Petroleum base stocks consist of many different oil fractions blended together. No two batches of oil are alike. Some of the molecules are long carbon chains which are affected by relatively low temperatures. Oxidation occurs in which the oil breaks down causing acidic gasses and sludge that form in the crankcase. As the oil breaks down it becomes thicker reducing low temperature protection. Then your additve package looses its effectiveness. The anti-wear, anti-foam, corrosion protection, acid neutralization, and VI improvers are only designed to last 7500 miles or so.

With synthetic oil which starts out with only pure basestocks and superior additive packages. It will last a lot longer. Some synthetics contain better detergents that help to keep your engine free of sludge and varnish.

A full flow filter must be capable of doing 2 things. Removing and holding contaminants,and allowing sufficient flow. They do this by sacrificing the filtration of finer particles. Your filter still becomes saturated rather quickly. If your filter becomes too dirty, it is desinged with a by-pass, allowing non-filtered oil into your engine, to maintain proper lubrication.

This is why we must change our oil so often.

Now if you use some synthetics and better filters(more effeciency, and capacity) you can extend you drain intervals. If you want to extend even farther you can install a by-pass filter which is capable of filtering contaminants smaller than 1 micron. With oil analysis to ensure that our additives are still working, oil changes can be extended way beyond normal drain interval.


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Lube-Direct

[This message has been edited by msparks (edited 01-03-2000).]

 

I had a BLACK Jeep CJ7 in Phoenix. The plastic valve cover leaked oil on the very hot exhaust manifold. Not able to find a metal valve cover to fix the leak, we soon tired of smelling the oil burning, not to mention a fire hazard! A friend suggested Amsoil. It worked!! The oil still leaked but never burned, even when the weather reached 126 degrees. I think one reason our oil turns black,is because it burns.

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White 97 XLT SC 4.6, 4X4, 3.55ls, tow pkg, long bed, Rhino liner, Owens running boards

 

Charlton Heston would tell you this: Oil doesn't kill people, people kill oil, and bad people do both.

 

I have found that changing oil and filter every 4500-5000k does other good things for your rig...That is it gets a good check over in other areas as well...

I do it at the same dealer and get him to give it a good look over while he has it...Many times they find something that needs looked at and that helps me in the long run have less problems...

 

Gasoline makes oil go bad. In many engines not all gasoline and components in gasoline get burned off. These work their way into the oil contaminating it.

As mentioned earlier, synthetics start with fewer contaminants and can go longer between changes.

The worst full synthetic you can buy is often better than the most refined conventional.

 

When I bought my new Jeep, the dealer insisted I change the oil every 3 months. I informed him the Jeep was a toy and might get 1500 miles a year put on it. He still insisted that I change the oil every 3 months regardless of mileage to keep my warranty valid.

Does oil really go bad sitting in my oil pan? I doubt it.

 

Its not the oil that goes bad but the by-products of the combustion process. This puts water and acids into the oil. If you changed the oil and NEVER drove it after the oil change then you could probably leave it in the vehicle longer. I do not know if the oil react's with the engine metal when it just sits in the engine but dino oil has impurities in it.

 

Before spending any more time on the oil question I would ask that our gentle readers consider this:

How many cars/trucks have been put down because of oil related failures? I think keep some level of oil in there and worry about the rest of the failure reasons, and have a nice day,

 

NO! NO! The voice of reason! Go Away!

I have to achieve my keyboard keyclick quota for today.

 

In my own experience, I have found that no matter what type of oil you use, when you change it regularly your engine will most likely first go down and need repair from top end problems. The oil you need to be looking at is your top end lubrication.

My main problems have always been ring, valve, valve guide, piston, and top cylinder wear. My bottom ends usually lasted through two sets of rings and exhaust valves. Obviously, better top end lubrication, combustion byproduct control, and air filtration are bigger issues than type of oil for the average driver. Fuel injection reduced the problem to some extent with better fuel mixture control. Few people kept their automatic chokes adjusted properly in the old days. Fuel additives and air filters are what need improving. While Marvel Mystery Oil helps to prevent hard combustion deposits, air filters have a long way to go to really filtering the small dust particles out of air.

One reason for my good luck with bottom ends is that I usually used good oil filters like Hastings, Wix, AC Delco or Motorcraft instead of the bottom line filters that many people bought. I caught on early on that Fram was slipping. Castrol and Valvoline always maintained oil pressure out to 3000 miles better than Pennzoil and Quaker State.

Even the Amsoil foam air filter is inefficient according to one independent test I read. It's no better than a K&N, if as good, and much harder to clean and service. The synthetic foam doesn't really soak up the tack oil the way the cotton cloth of the K&N filter does. Air filters need to filter to much smaller particle sizes to be really effective.

I just talked to a top Honda local mechanic today that runs his own shop now. He regularly goes 7000 miles without an oil change when on trips and says you don't need to change more often than 5000 miles unless really driving under tough conditions like short trips or high heat and high RPM's. He uses synthetic oil in his race engines. I believe exactly the same way. Short trips in cold weather can really wreck havoc unless there is a long trip between every few short trips. The Honda mechanic also agreed with my father, who was once a Ford dealership mechanic as well as private shop owner, that cars that use no or very little oil need a gas treatment to prevent upper cylinder wear. Dad always mentioned Marvel Mystery Oil, but also said diesel oil would do as a passable substitute for top end lubrication. You have to dope the diesel oil at a much higher level as it is much lower quality than MMO.

 

My family's new Honda's recommended oil change is every 10,000 miles under normal schedule and 5,000 miles under severe. It should be noted that the oil is standard issue dino 5W/20, not synthetic or blend.

Since my parents do not drive that much, we asked the dealer about oil changes based on mileage and time.

The dealer informed us to do our oil changes based on mileage and not time, UNLESS we regularly drive it 5 miles or less. If we drive it enough to burn all condensation, contaminants, etc., then mileage based oil changes is fine, even if it takes us a year to hit 5,000 miles.

BTW - My F150 I change every 3,500 miles, but I know I can go more than that, I just don’t! Call me old fashioned