Your Max OCI (in months) With Synthetic Oils ?

Sep 10, 2010
Providing you do not reach your preferred OCI mileage first (i.e. 5K , 7.5K , etc.) what is the max length of time (in months) you establish as part of your OCI routine with synthetic oils ? For most of us - it's usually a mix of highway and suburban driving with the occasional stop & go city trip thrown in here and there . Owners Manuals state either 6 months or 12 months max but of course there may be other variables such as whether you drive a GDI engine vehicle or not ? Since my main vehicle has a GDI engine , by 6 months the oil becomes fairly dirty (soot) and is starting to become a bit fragrant (fuel dilution) ... So , what is your max length of time you establish as part of your OCI routine with synthetic oils ?
2 yrs but I'm not really sure. I go 10k miles and don't drive often since I've started working from home. But when I do drive it's usually a 30 minute drive with highway miles.
9 months has me at 5k on the Jeep - OLM has plenty left and that surprises me because I short trip often.
Pentastar capacity was lowered from 6 to 5 quarts - so I go ahead and change oil & leave the filter for 2 OCI … don’t need ramps …
5k miles or one year in the 4Runner and Ranger for mixed driving. 2 years for the F150 that goes 1.2k miles a year. I changed the oil in the B2500 Van 6 years ago, parked it and it hasn't moved since.
one year/10k mile oci with vw-spec synthetic oil is vw’s rule for my passat.

when my mom was living i insisted on a synthetic oci at the one year mark for her base 2006 toyota highlander. mileage was 6-7k but it was around town driven slowly by an elderly lady so an annual synthetic oil change was warranted imho. the date coincided with the annual state inspection renewal, and the dealer did a more thorough, free inspection, plus washed and vacuumed the car, so was a good thing all around.
i never get to go a year between changes before hitting 10k but I wouldn't be against using the same oil for 2 years if i only drove it a few thousand miles a year and isn't the type to have dilution issues.
Six months if frequently short-tripped and idled to warm up in the winter, which tends to be the case for our vehicles. If the trips were infrequent but generally long enough to get the oil up to operating temp for a while, I wouldn't hesitate to go a year.

As others have mentioned, dumping oil that has a detectable fuel odour in favour of a fresh fill feels right. An analysis of the 6-month old oil to determine if fuel dilution (or anything else, although unlikely with low mileage) is actually an issue would be the more evidence-based approach.
I changed oil in my son's Jeep last night and did our Jeep as well. He ran his OLM to O% and I think it must have been about a year. I only go about 6 months on our Jeep GC. We rotated his tires last night too. I used the Mity Vac on both vehicles and you can see it on the second picture by my Ford F-150 tire.


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In retirement I'm not accumulating very many miles on my vehicles. My Mazda CX 5 only about 5000 miles per year so I pretty much change it annually and my Jaguar will probably only accumulate 3000 miles this year. The Jag gets free oil changes each year as part of the warranty.

In both cases the oils used are top of the line synthetics. Mobil 1 EP in the Mazda and a specially formulated Castrol Edge Professional in the Jaguar. So I don't worry about the oil & engine conditions. But I wouldn't keep either of those oils in either car for more than a year.
I don't have a firm rule, but probably 2 years. I see people wasting perfectly good oil all the time, all because it was in the sump for some arbitrary time period. Not long ago my mom changed the oil in her minivan because it had been ~18 months since the previous change. Turns out that the oil had about 60 miles on it. What could possibly be bad with oil sitting in a sump unused?