Do a UOA and find out how much life, if any, the oil has left to it. Anything else is a shot in the dark. Just curious what filter is on the engine now? They make filters for extended drains that might allow you to run the oil and filter combo, up to, and beyond 15,000 miles. The only thing you'll have to do is check the oil. But as I already mentioned it is best to do a UOA and see just what's going on.
At 12k miles?
I figure that the oil would have had it after 12,000 miles.
Oil filter would do little if anything. You would only be draining about a pint and then topping that off.
So in a 5 quart system you would be changing out about 10% of the oil capacity, if you hadn't burned any in the past 12k miles.
At 12K you got your money's worth, drop it all and refill. And do a UOA to make sure that you are good at 12k intervals.
It's a Fram 7k (?)(extended mile one) and the oil only has 3500 miles on it but it's taken ober 4 months to get that many miles cause it's mostly low city miles, moslty 1-5 mile trips in the past two months.
I'm thinking you ran the oil 12,000 miles. Mobil 1 four months old 3500 miles, no problem, do nothing other than check the oil. Perhaps at 6 months, or 6000 miles I'd do an OC or draw an oil sample and have it tested. That will eliminate any guess work, and you'll know how the oil/filter combo is working for you.
I'm confused about what's going on. It almost sounds like you're changing your oil and filters on different schedules.
How many miles are on the oil that is currently in the car?
How many miles are on the filter that is currently in the car?
Just change them both at the same time and reset the clock.
OP wants to know if he use M1 (not EP version), can he just change the Fram oil filter midway of an OCI without changing the oil.
I would paid a little more for quality filter and do a complete OCI. Changing only low quality oil filter is a real mess, time consuming and actually cost more.
Would that benefit the oil/car any? Just wondering if it'd be good for the engine.
Yes, WHICH oil are you talking about??? Mobil Clean 5000 is going to call for a very different answer than Mobil-1 Extended Performance. As for the later, it's designed to go 15k miles in a good engine, so I'd ask, why change anything? As for MC5K, you're already 7k overdue to change. Then there's the question of UOA. You don't need to do them like an OTR trucking company (many UOA critics mistakenly assume that deciding when to change is the only reason or benefit in UOA). But one done now, with a TBN, would give you a starting point from which to start evaluating what OCI is best for you.