I have a 15 year old car with 83K miles on it. It is known to have tight bearing tolerances and passages. It is also known to have leaky seals and gaskets. Since I bought it I have been using Quaker State High Mileage dino oil due to cleaning, anti-wear and seal conditioning additives in addition to its high VI. I have been using an OCI of 3750 miles and, recently, I have switched to a K&N oil filter with 60% larger volume. I am thinking of pushing the OCI to 6000 miles and here is the reasoning.
Subaru suggests an OCI of 7500 miles or 3750 miles if one drives in harsh conditions. Harsh conditions are extreme cold or heat or driving in a dusty environment or making lots of short trips. The only thing that applies to me is the extreme cold or heat and that is only for about half the year as I live in upstate NY. Splitting the difference of the OCIs comes out to 5625 miles.
If I am thinking about longer OCIs, I will only do it if I use a synthetic like Mobil 1. Vice-versa, I will only go to the cost of a synthetic if I can extend my OCI. If I understand correctly what people claim about synthetics, my oil should be in good shape beyond 5625 miles if I am using a synthetic and only drive in harsh conditions half the time.
While the oil may hold up in terms of not becoming excessively oxidized and acidic, there is still the issue of contaminants finding their way into the combustion chamber and, hence, the oil and oil filter. That is why, if I understand it correctly, people still change oil filters when they switch to synthetics and extend their OCIs. But the larger K&N filters I can use on my car are 60% larger than the stock filter. 60% more miles would equate to 6000 miles if the reference point chosen is the lower 3750 mile number.
So, given that I don't drive in extreme conditions year round, I am potentially switching to Mobil 1 HM and I am using a 60% larger filter, I think a 6000 mile OCI is fine.
Comments?
Subaru suggests an OCI of 7500 miles or 3750 miles if one drives in harsh conditions. Harsh conditions are extreme cold or heat or driving in a dusty environment or making lots of short trips. The only thing that applies to me is the extreme cold or heat and that is only for about half the year as I live in upstate NY. Splitting the difference of the OCIs comes out to 5625 miles.
If I am thinking about longer OCIs, I will only do it if I use a synthetic like Mobil 1. Vice-versa, I will only go to the cost of a synthetic if I can extend my OCI. If I understand correctly what people claim about synthetics, my oil should be in good shape beyond 5625 miles if I am using a synthetic and only drive in harsh conditions half the time.
While the oil may hold up in terms of not becoming excessively oxidized and acidic, there is still the issue of contaminants finding their way into the combustion chamber and, hence, the oil and oil filter. That is why, if I understand it correctly, people still change oil filters when they switch to synthetics and extend their OCIs. But the larger K&N filters I can use on my car are 60% larger than the stock filter. 60% more miles would equate to 6000 miles if the reference point chosen is the lower 3750 mile number.
So, given that I don't drive in extreme conditions year round, I am potentially switching to Mobil 1 HM and I am using a 60% larger filter, I think a 6000 mile OCI is fine.
Comments?
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