Why Oil goes Bad

[Runner]

"Doesn't that depend on how it's used and the service conditions?"

Absolutely. I guess I was referring more to the fact that the manufacturers all recommend changing oil yearly, regardless of how many miles you put on the vehicle. My truck, for instance, doesn't get driven more than about 1,000 miles per year, but the manual says to change the oil yearly anyway.

Seems a waste to drain out 6 quarts of oil that is practically new and replace it....

 

[jlawso21]

I have an 03 Envoy with over 200,000 miles on it. I change my oil when the light on my instrument panel says "change oil" or 10,000 whichever occurs first.

When I bought it I was skeptical of the intervals but I did what the dealer told me. All my oil changes were at 10,000 miles or greater until I started pulling a boat and my tractor. Some of those changes came after only 2000 miles, again when the light on my instrument panel told me to.

I was told that the car's computer monitors all conditions, particularly heat, and will tell you when you need to change it. Like I said I was skeptical at first, now I am not. My car's engine still runs great, mileage is good, and it does not use any oil between changes. I would not have believed this possible 10 years ago. The oil I use (dealer ) is Castrol synthetic. I am planning on 300,000 miles and hoping

john

 

[John Morgan]

Another great example of beppinton's position. Chances are your Ford dealer is using Motorcraft, which fits perfectly into the same catagory as Castrol, Valvaline and so on. 5000 miles in stop and go traffic when using a quality oil is possible with little or no detrimental effects. Ask the dealer to back it up with an analysis of the oil to insure mechanical stability. The problem is the oil companies rely so heavily on consumer ignorance. They run stupid commercials of guys with mullets with their hair blowing when they pick up oil. Unfortunately, these are the things that influence people to buy their product. Not one time in any oil commercial do they ever tell you why it works. On the opposite side you have Amsoil distributors you are taught how to sell oil but not what makes Amsoil worth buying outside their claim of 25,000 mile oil changes. Problem with that is, no samples, no consideration of the duty cycle, no support, just the salesman claim. I wish they would spend more time educating than selling. It takes time to establish a drain interval based on mechanical stability. It takes evaluation to determine the true savings involved in using one oil or another. How many of you use an oil because thats what you've always used or someone told you to use it? Don't be afraid of research. Look it up, ask questions, get some education in how oils and greases are made and why they work. You will be surprised in how much of it is pure profit for the company.

 

[SPYDERLK]

"Doesn't that depend on how it's used and the service conditions?"

Absolutely. I guess I was referring more to the fact that the manufacturers all recommend changing oil yearly, regardless of how many miles you put on the vehicle. My truck, for instance, doesn't get driven more than about 1,000 miles per year, but the manual says to change the oil yearly anyway.

Seems a waste to drain out 6 quarts of oil that is practically new and replace it....

If thats a whole bunch of short trips thats bound to be some pretty damp oil - even tho not very dirty. I would be tempted to switch it over to something that gets longer use duration and get the remainder of its life.
larry

 

[jinman]

For many, many years (until last year, in fact) I changed oil & filter in my vehicles every 3k miles. Every dealer I knew of in the Dallas area said they considered our heat, air polution, stop and go traffic, etc. to be "severe service", but last year, my Ford dealer started recommending 5k mile intervals instead. My last oil & filter change cost $29.43 total at the dealer. I've gone 4k miles each of the last 2 changes, but old habits are hard to break.:laughing:

Bird, I just don't see how anyone would consider it severe duty on any automobile under standard conditions. Without pulling a trailer or constant start-stop under acceleration, I just don't see how our temperature or smog would cause more wear. The reason I feel like that is the thermostat holds the engine at the same temperature so the oil temp should be the same in the winter or summer. Also, a good air filter will surely filter out any dust or contamination that would harm the cylinder walls. After all, fuel-contaminated air is exactly what we want inside a cylinder and we exhaust more concentrated polluted air than any air pollution in a city. I just don't buy that an auto used to haul one or two people around suburbia is severe service. With today's cleaner fuels and much better fuel controls with injectors, I think contamination is far less than on a 60s or 70s model gas guzzler where the 3000 mile interval made sense. On a 60s model car, if you got 100k miles it meant you did very well. Today, cars easily exceed 200k with just routine care. I'm one of those people who believe the 'good ol' days' are right now. An oil change between 4k and 5k miles is excellent care.

That's my story, and I'm stickin' to it.:laughing:

 

[Bird]

I pretty much agree with you, Jim. But you know we have 2 vehicles; a 2001 Ford Ranger with the 4.0L V-6 engine (79314 miles on it) and a 2002 Ford Crown Victoria with the 4.6L V-8 engine (59340 miles on it) and the last 2 years we've put about 7k miles a year on each. We make a lot of 3 to 5 mile trips living in town again. I used to routinely put about 30k miles a year on my car and now we aren't putting 15k a year on the two combined.:laughing: At the rate we're going, I figure if I keep them serviced, they should both outlast me.:laughing: Of course, I'm kinda particular so in spite of not wanting to spend the money, if any little thing goes wrong with one of my vehicles, I'll get it fixed and pronto.

 

[MHarryE]

I have 2 German cars, one a 2000 and the other a 2008. I have had the dealer change oil by the computer. For the 2000, that has been at around 15,000 miles. It now has 120,000 miles and is still at the full mark when oil change time comes around. The 2008 went to 22,000 miles for its first change but that was when I was driving a lot. Now I've retired and they say once a year no matter what the computer says. They pay for the change (well, I guess I paid for it when I bought the car) so it doesn't matter. I have often wondered why I change so often in my F-150 but now it makes sense - it gets the semi-synthetic that my Ford dealer sells instead of the pricey synthetic for the German cars. My excavator and older Kubota live on Rotella 15W-40 but my new Kubota will go to synthetic at its first change.

 

[lostcause]

i think most of us understand that changing the oil in an engine is part of the routine maintenance, and the only thing to debate is at what intervals we do it at. newer oils and better engine management systems are undoubtedly allowing longer intervals between changes, but there is still an upper limit on how far you should go for vehicles that don't get driven much.

i've tried to do a lot of reading to understand how oils work and to try to figure out what oils are better for older and newer engines, and there is so much information out there that it can be hard to decipher it all. one thing i did find was that your standard organic multi-grade oil, is really made from the lower grade oil, so a 5w-30 is made from a 5, and not a 30. my understanding is that the additives in the oil allow it to work as a 30 when it is at temperature. as the oil is used and gets older, those additives wear out, and the oil will slowly revert to the base 5 weight oil. i'm sure it takes a lot of time and use for this to happen, but it is certainly food for thought, and does put into perspective that oil will not last forever. synthetic oils are not made the same way - i actually haven't bothered to figure out how they work yet.

 

[jonyyuma]

Both of our cars (2006) (2010) call for 5w20 oil, so I use synthetic in both of them. Dino oil change was recommended at 7500. I use only the factory engine oil filters, and have never had an failure before 200k, except a 6.2 chevy I bought used..

 

[sw03]

This may all be true but oil and a filer is so cheap, why not? I use medium grade motor oils in all my stuff with the exception of my Nissan Titan where I use higher grade stuff. Yes, I could go longer than 5,000 miles on vehicles or every year on my equipment and boats but why? Say I save $40 per year per vehicle what am I gaining? You can not replace the valve cover gaskets for that. I would rather have the piece of mind knowing its fresh oil and ready to go.

I know guys who do oil monitoring on things that use 4-6qts of oil. They change Just the filter once every 100 hours or so. Seems stupid to me to pay $30 to see if the oil is good, $5 for a new filter, and $3 for a qt of oil to top it off when they could just change it for less or the same $$$$

Chris

Sure UOA are stupid and cost more but the benefits are priceless here. They saved me a few times on car issues under warrenty and back in 2008 on a few Marine trucks, MRAPs (warrenty from CAT). Why do you think the US Army / Marines does not have drain times on their trucks?

I change my oil every 1 to 1.5 years based on a few years baseline every 6 months. I know how my engine runs for me so it saves me time, money, product etc doing it on this duration. My piece of mind is the based UOA I did (not it is new oil so I am fine) and do every 3 years and I do not like messing with used oil etc. I have better things to do in life...YMMV

If you have a bypass it will last forever (aka more then most drive to kill it). The trick is when you change the full flow filter and bypass you are adding to the add pkg so that helps.