Ughhhh, what?

If you drive the car longer, you put on more miles. Unless you are talking about running the engine in parking lots of long periods of time?

Driving highway miles where stuff is farther apart in USA is better for the engine. So this logic of yours fails, that USA should have some magic low 3000 number. If everything in USA is farther apart (more country roads and rural areas) then this should give USA folks and Canadian folks longer engine life, not shorter engine life.

Interesting that you pull some magic number (5000) out of a hat and apply it to all cars no matter what car it is. Sounds like pure B.S. to me. Sounds just like the “every 3 months” or “every 3000″ magic B.S.

All the cars I’ve owned with over 300K on them have had lots of other problems unrelated to dirty oil. For example, terrible rust and suspension issues, steering issues, transmission issues, these all can cause people to take a car to a scrap yard which has nothing to do with dirty engine oil.

Other times I’ve seen cars go to the scrap yard because the engine just wouldn’t start, and no one had time to fix it, and the car was rusty, and only worth a resale value of about $900 since it was old. Never have I seen a car been taken to a scrap yard due to an engine that seized because of dirty oil. Now of course there may be some cars which actually had seized engines due to dirty oil, but often it’s because of a combination of other problems unrelated to the oil, like windsheilds, suspension, rust, computers, low resale value, ugly paint job, not starting after sitting for years, etc.

What happens when people don’t change the oil is that the oil level goes down, especially on older cars. It can go down one half a litre or one litre after 3000-10000 miles. When this happens significant damage to the engine can occur. Not because the oil is dirty usually, but because the engine is starved. At least this is my experience – the only engines I’ve seen go bad are ones that have had coolant in the oil, or engines that have had the oil level go down way too low.

If you check your oil level frequently you can also monitor how dirty the oil is, and you can monitor for head gasket problems (coolant in oil).

In my opinion it is better to monitor the oil level than to change the oil. Also one can smell gas in the oil when checking it frequently.

If you top up the oil, you add new oil to the engine which dilutes the old oil. True that the old oil is still there, and true that if you are diluting the oil that much then you must have an engine in bad shape, but you still are diluting the oil making it cleaner than it was before.

I have had cars in the family that have had oil changes every 3 months regardless of kilometres, and all those cars lasted long (over 200,000km) except for the one that lost half a litre of oil due to a leak out the dipstick seal! This particular car, even though oil was changed every 3 months, had bearing failure and a knock after it was driven with very low oil level. I realized that the major factor that damaged engines was a loss of oil, not how much you change the oil. Another car I had with bearing failure had coolant in the oil once due to head gasket failure.

Another issue to consider is that other things will happen to your vehicle anyway. Most people abandon there cars or sell them long before their engine fails due to not changing oil. Usually the suspension, rust, electronics, even cracked windshields, and a combination of many things cause a car owner to sell or give the car away. What does this mean? It means you should not change the oil as often because you probably won’t keep the car for 500,000km anyway.

I’ve seen far too many cars in scrap yards with engines that are still very good. Some of the cars my family has owned has gone to the scrap yard purely because of suspension and rust problems, especially front wheel drive cars with all sorts of suspension/drivetrain issues!