Oil change - miles vs. time

rbirns1

When recommended oil change interval is 5000 or 10000 miles, but you only drive 2-3k per year, how often should you change the oil? Even with synthetic, is going years between changes safe?

PF_Flyer

Lots of different views on this, but if you're not putting a lot of miles on, I agree with this paragraph from a Scientific Amrerican article that cites information from Edmunds

According to the automotive website Edmunds.com, the answer depends more on driving patterns than anything else. Those who rarely drive more than 10 miles at a time (which doesn’t get the oil hot enough to boil off moisture condensation) or who start their car frequently when the oil isn’t hot (when most engine wear occurs) should change their oil more often—at least twice a year, even if that’s every 1,000 miles, according to Edmunds. But commuters who drive more than 20 miles a day on mostly flat freeway can go as far as their owner’s manual recommends, if not longer, between changes. As a car ages, more frequent changes might be in order, but that’s for a qualified mechanic to decide on a case-by-case basis.

kyfdx

We should get @thecardoc3 in here to address this.

thecardoc3

rbirns1 said:

When recommended oil change interval is 5000 or 10000 miles, but you only drive 2-3k per year, how often should you change the oil?

What does your owners manual say about the time interval? It's pretty common today to see service schedules have varying mileages depending on the drivers habits and even varying time intervals. When the manufacturers specification requires a "synthetic" or "synthetic blend" and you make sure that the product you choose is approved to meet their specification you will see something like 7,500-10,000 miles for North American or Asian cars and up to one year duration. If the original specification was for a conventional product then you will see something that will allow you to go somewhere around 5,000 miles and up to six months. The difference is the ability of the oil to control crankcase acids which are caused by blow-by gasses condensing inside the engine and PCV systems. Once an oil loses its ability to control crankcase acid production the oil will sludge very quickly. Short trips where the engine does not get to reach normal operating temperature for a long enough period of time are one of the major contributors to acid production.

rbirns1 said:

Even with synthetic, is going years between changes safe?

No. There is no way that should be recommended even if the oil can in fact manage to protect the engine. There are just too many variables in play for anyone not checking the car on a regular basis to account for and a number of them have nothing to do with the engine oil. You still need a qualified person to inspect the rest of the car for trouble from time to time and a proper oil change service interval allows for that to be done.