Why do the manufacturers recommend changing the oil every 3 thousand miles?

Question

but the synthetics say you can go all the way to 15 thousand miles. In fact the corporation I work for goes 10K on conventional oil with their whole fleet?

Answer 1

Oil changes are relatively inexpensive compared to replacing worn out parts on an engine. If your manufacturer requires an oil change every 3,000 miles, I would stick to it. Some manufacturers recommend oil changes every 5,000 (Toyota) or 7,500 (Nissan - light duty use and Honda). The reason some manufacturers choose a higher mileage interval is due to the quality of their engines. Take a look at the oil on a Honda at 5,000 miles (still has some golden hue). This is because the engines are built with a very tight tolerance and there are not as many contaminants in the engine oil(combustion chamber leakage). This is also the reason why these engines last so long and pass smog tests so easily.

Going 10,000 miles on conventional oil is very risky, however your company may feel this is ok if the vehichles are not abused.

Synthetic oils last longer, because the oil molecules are man made (closer to perfect) vs conventional oil. The more consistency in the molecules, the less molecular breakdown will occur and the oil will last longer. An interesting test is to put a drop of conventional oil in a frying pan. Heat it up on your stove (only use one drop, because it can become flamable). Watch is turn from a nice golden hue to brown, then to black. Do this with a synthetic. No change in color. It doesn't degrade from heat.

Synthetic oil also coats engine parts better, so you have less "dry start" wear.

European manufacturers require synthetic motor oil, because of the quality of the oil. Porsches can now go 25,000 miles between oil changes and you know how hard people drive these cars.

I hope this helps you make a good decision.

Greg

Answer 2

Ok as Ive only been involved in body work in the restoration area, I may not know exactly everything about mechanics but this is the way that I understand it.
A manufacturer will recommend 3000 mile oil change for 2 reasons. 1) fresh oil will prolong engine wear equaling less warrenty coverage issues. 2) The oil company recommended will absolutely make more money. Now regardless of what anyone tells you, ALL oil has a break down issue with use. heat, friction, etc. Synthetics may wear longer as youve already been told. This I dont know for sure. You dont mention the year of car that you are driving or the amount of mileage on it. Lets say that the car is older. This means that there is absolutely wear to the engine and changing the oil more frequently will remove certain partricles floating around inside instead of trying to suck them up the oil pump. Ive heard most all of the pros and cons on several of these issues but still prefer to be on the safe side and take good care of my auto by changing the oil every 2500 to 3500 miles. This way, there is no guessing about wear. One more thing to remember is that even though you may not have many miles on the car, time itself has a wear on oil. Hope that this helps.

Answer 3

The manufactures oil change recommendations at 3000 miles are for conventional motor oils.If you decide to go to a synthetic,you can at least double the oil change interval.

Answer 4

lots of places "autozone, firestone's, whoever" say 3000 mile oil changes there looking to sell oil changes.... look in the owners manual n go with that... my x-gf's civic recommended 10000 mile oil changes on conventional oil, a friends tacoma 7500....

Answer 5

greed
my old Toyota Higlander
did under the milegae and Firestone said not to worry
Will take you money if you want to pay but you can go longer if not exceeding the mileage