When to change oil on low mileage vehicles

I have a 2003 Mercedes ML320 with just over 40k miles. It is garage kept, and has had all the oil changes, and service requirements done by a Mercedes dealership. My question is should I change my oil based on the mileage and the oil life computer, or should I change the oil based on the time since my last oil change. As you know this vehicle takes 8 quarts of Mobil 1 so oil changes are not cheap. I also have the same question for my 2008 Toyota Corolla with 6k miles again garage kept with all oil changes and service requirements done by a Toyota dealership even though the oil change on the Toyota is much cheaper when do you recommend I change my oil. I live in Charleston, South Carolina, both vehicles are driven at least once a week far enough to get up to normal operating temperature.

Sam, In South Carolina

Every 5k with the Mobil 1. I do my 06 HEMI Charger every 5k using 7qts of Mobil 1 @ 6.99 qt. and a $6.00 WIX filter.
Every time someone asks a question here regarding oil change intervals it becomes a major discussion because everybody is set in their own ways. You are going to get so many different answers here, you are just going to have to decide for yourself how much the life of your MB engine means to you. If you have been servicing your MB on a regular basis and feel good about it, go with it.


Mercedes puts an oil life monitor in the car, you paid for it, why not listen to it. Your Toyota is doing about 3000 miles per year,I would change it twice a year in my climate (cold and snowy) and once in yours.

I believe MB (BMW, VW etc) says use oil life monitor or every year whichever first. That large oil sump helps a lot. Remember to check oil level over these periods.

The maintenance schedule should list a time interval, as well as a mileage interval. Since it’d take a couple years to go the mileage recommendation, follow the time recommendation.

As I recall the computer uses time as a factor. You can check on that, and if I am correct, they you are good to go following the computer’s instructions. I would double check the owner’s manual to verify that there is not special instructions for low mileage drivers.

Yep…follow the computer as directed or altered by what the owners manual states. GM’s OLM limits it to one year, but since most pre-computer directed Euro’s went for 18months and/or some higher mileage, I can’t see them devolving to anything “less”.

The Toy should be able to go once a year.

Side note. It takes about 20 minutes or 12/15 miles to fully thermally saturate an engine. That’s for the oil to reach full operating temp …and therefore normalized viscosity. You reach most of that in about 9 miles/10 minutes. Some of the smaller sump Euro’s that have heat exchangers can do full oil temp in about 9/10, but larger sump Euro’s, even when equipped with exchangers can take up to 45 minutes for full warm up. Coolant is warmed much more quickly but only ends the fuel enrichment stage. The oil takes much longer.