Recently I posted a thread with pictures of the FL820s filter I cut open from my wifes F150 when I changed the oil over the weekend. Various posters pointed out that running synthetic for only 5,000 miles as I tend to do on both of my vehicles is simply a waste. I thought about this for a while and decided that I wouldnt be against extending out OCIs but first I want to post a few lines about both the F150 and the Ram and the reasons why I chose this interval and get opinions on how long I could SAFELY run these oils. I refuse to pay someone to analyze my oil so that is out of the question, I would rather spend that money on 6 more quarts of oil and a filter as the whole idea IMO of extending OCIs is to save money. 2005 Ford F150. 4.6 liter engine, 108,xxx miles currently on clock. Currently running Mobil 1 5w20 and a M1 filter. This truck is drivin mainly short trips. My wife drives it to work, which is a few blocks away from the house, at least every other day. She also drops off/ picks up my daughter from school which is a few blocks from the house in the other direction. So at the very least 4 short trips a day where the engine doesnt even get up to operating temp much less the oil. 2-3 times a week she will drive it to whatever grocery store in town and the furtherest one is about 5 miles away, stop and go the whole way. So, severe service if I ever saw it. Maybe, the truck might see highway speeds once every 2 months or so, and that is a huge maybe. This is why I chose the 5,000 mile OCI and mostly this gets changed on time rather then mileage. She has accumulated 4,000 or so in 6 months or so this year, but that is only because of a few out of state trips when my dad was sick. He has passed on by now so this service is likely what this truck will spend the majority of its life doing. 2002 Dodge Ram 1500. 4.7 liter, 159,500 miles currently. Current oil is Mobil 1 5w30 and M1 filter. This is the one I am having trouble with. I was originally going to run conventional in it, but read about problems these engines are prone to with sludge. Therefore I decided on synthetic and 5,000 mile intervals. This truck does short trips around town 2 weeks out of the month and mixed trips the other 2 weeks (my work vehicle, I work 7 days on, 7 off). As stated on my weeks off it does short trips around town, and a trip here and there. On work week it will see 3 days of 142 mile round trips, and the other 4 days are a highway run of 20 miles in the morning, several short trips and idling, and another 20 mile highway trip in the afternoon. Sometime this week the oil will be changed in here, but with a Mopar M0-090 filter this time. Any input is welcome and I am sorry about the long post. Of course I like the 5,000 mile OCI because its easy to remember, and the tires get rotated and zerks get greased at the same time, but I am willing to consider another way if its better (10,000 would be ideal too but dont know if regular M1 could handle it). Thanks in advance for any advice or opinions.