Add a quart, extend the OCI?

[otis24]

I have decided to do my oil changes at 4000 miles. I had 2800 miles on my oil, leaving me 1200 miles to go before my next oil change. Coincidentally, I left on a trip for vacation (and am there now). When I get back home, my oil will be at 4000 miles.
However, just prior to leaving on my trip, I was 1 quart low and added a fresh quart (Havoline 5W/20). 1 quart is 20% of my Dodge Grand Caravan's oil capacity. By adding a "fresh" quart, by how much am I extending the overall life of my oil? I mostly drive short distances (2-3 miles in cold South Dakota weather). If adding a fresh quart between changes becomes routine, am I safe pushing my OCI to 5000 miles?

 

[Gary Allan]

Hmm ..what time frame does it take to get to 4k and 5k? If most of your driving is of the shorter variety, then you should be using time as your standard for the OCI.

..but, to answer your question .. I would think that one quart top up should extend your sump for 1000 miles from where it's at from a TBN standpoint. That doesn't necessarily mean that the oil is in favorable condition otherwise (fuel, water, visc, insolubles, etc.).