I agree, but I’m an exception to the rule, and I’m sure there are others. I live in a rural area and the nearest town is 10 miles away, long enough for the engine to reach operating temperature even in cold weather. I don’t do stop-and-go driving or pull a trailer so my oil temperature never gets above normal. I’m also a low-mileage driver. So, am I going to throw out my synthetic oil after X months because I don’t have an oil life monitor? No.
If that’s true, every vehicle’s owner’s maintenance manual should be located in the fiction section of your local library. If the idea of keeping oil in your car for 25,000 miles is to save money on the cost of oil, it’s not a gamble I’m willing to take. Changing oil is cheap.
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No way I’d do that in my car.
Anyway, if I understand the OP’s question correctly, she’s using the correct oil as specified in the owners’ manual, but simply doesn’t put many miles on the vehicle and would like to know what would be a good time-based schedule for oil changes. I commend her for asking these questions.
The answer will be subject to many biases and preferences… and maybe even some myths. IMHO the bottom line is that the engine is too valuable to try to extend intervals to the time frames many owners’ manuals now recommend. Personally, I like the six-month suggestions. Texases explained the reasoning beautifully. Oil cannot be too fresh, only too old, and changing it every six months should be affordable.
One caveat: this does NOT mean you should not monitor your oil level. Making sure your oil level is high enough via checking the dipstick should be done at least weekly, and always immediately following an oil change before driving off… then again when getting home in case the plug was not properly tightened. Not doing so has resulted in a lot of destroyed engines and premature wear.
For the record, years ago I got my oil changed at the dealer’s (new vehicle), drove it (less than two miles), got out and saw my oil running down the parking lot where I’d parked. The plug was loose. Had I continued to drive further, I would have had a toasted engine in a new vehicle. I never again drove away from a garage without first double checking the work performed.
But let’s not forget that the filter used is not the $6 generic screw-on type, and that these engines hold about twice as much oil as a similarly sized engine in a typical family sedan. There’s much more to it than just conventional vs. synthetic.
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The time interval is based on the average driver putting two to four drive cycles a day on the vehicle. A drive cycle is cold start, fully warmed up and shut down warm (hot). The hot (normal operating temp) shut down is the hardest on the oil. During operation, oil is flowing over hot surfaces, gets hot and returns to the pan to cool down. The oil only spends a few seconds in contact with the hot surfaces before returning to the pan.
At shut down, a little oil is trapped on those hot surfaces so it absorbs a lot of heat before the engine cools down. Heat causes the oil to break down. As the oil goes through many of these cycles, it tolerates the heat less and less. You have to change the oil before it reaches the point that the residual oil begins to form sludge or coke. Coke is a gritty substance. Both will cause damage to the engine.
If your low mileage is due to only driving your car once or twice a week, you can ignore the six month recommendation, but if your low miles are due to short trips, you had better follow it.
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+1
Plus, BMW specifies a “European-spec” synthetic oil that is not the typical synthetic oil that you find in The US.
This “European-spec” oil is specifically compounded for very long oil change intervals. You won’t find this oil at Wal-Mart, and where you do find it, it is more pricey than the typical synthetic oils.
Oh, I wasn’t even going to go there. Imagine the consternation if we said that in addition to needing to check the oil level regularly and add as needed, you needed to use an oil that wasn’t available at every discount warehouse?
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The current state of oil grades is such a mess, with various companies coming out with various specs. GM has theirs, as do VW, BMW, MB, etc. Used to be so simple…
Oh, I don’t know that I’d say current. The VW/Audi oil spec 502.00 dates back about 15 years if I recall, MB a little earlier than that. Euro oils have always had their own spec, but the extended intervals and sludge issues in certain models have just made it more well-known.
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I gave you a Like because you have many good points. Short trips are hell on an engine, and the colder the temperature during a cold start and cold shut-down, the worse it is. If it’s a nice hot day and I do a short trip, it’s probably not too bad. But short trips are as bad as stop-and-go driving a trailer-hauling.
VDC - great point! When I talk about synthetic oil I’m only thinking of the real thing, the expensive ones which Walmart never heard of and which I assume are as good as Euro-spec. I exclude cheap synthetic, like when a company has a reputation for terrible conventional oil and then got into the synthetic business. My personal favorite is Amsoil because it’s expensive, it was the first synthetic in the U.S. or maybe the world, and it was developed for jet engines after WWII.
Spock says " That is not logical "
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Agreed
Some of the most expensive brands are far from reliable
Jaguar
Land Rover
Benz
etc.
Our 2009 Chev Cobalt specifies oil in a container marked with GM6094M. Change the oil when the oil minder is down to 0% or slightly before or at one year max. The last three oil changes were done at 9569, 10344 and 10370 miles. The engine now has 97k miles, doesn’t burn any oil and runs like new. At 7000 miles with synthetic oil your Subaru should be just fine but your one year maximum appears to be past. I would not worry about that. I routinely let my two motorcycles go to two years to change time due to few miles traveled and so far there is no problem. Neither burns oil and both run like new.
You might want to write to Subaru to ask them to get modern and equip their vehicles with an oil minder. It’s a great feature that takes the worry and need to remember away from oil change needs.