I'd say one of the main advantages of changing your oil every 3k miles is that you can check to make sure everything is okay when you are underneath the car and also if you are leaking coolant into the crank case, you can spot is earlier. However, I know this does not occur very often, but is still a benefit. I myself have asked the same question over and over again which type of oil to use. I look at it this way:
5 quarts of Dino = $5.40 @ $1.08 ea.
5 quarts of Synthetic = $21.00 @ $4.20 ea.
Changing oil every 3k miles to me does not warrant the use of an oil filter greater than $3.00, so something like a Purolator Premium Plus or STP with a nitrile ADBV will do. So we are at $16.80 every 6,000 miles.
If going the distance with Synthetic where it will be in use for more than 2 season (fall, winter, spring), I would look for a quality oil filter with a silicon ADBV, something like a WIX filter which costs me ~$5.50. So that means $26.50 every 6,000 miles.
That's a cost difference of ~$9.70 every 6k miles. Not really worth it to me as a poor college student, but as Pscholte stated above, $9.70 a sunken cost that would inevitable go to something like bean burritos at your local Taco Bell . Taking an average distance traveled to be 12k miles per year, that is $19.40 per year. However, if I felt that sythetic oils can protect equal to or better than Dino oil up to say 8,000 miles, then I could justify the cost, but I have only seen a few UOA's where people have posted results with more than 8,000 miles. That is why I like what 3MadPonchos has been doing. It is tests like those that make me a believer.
If I had a brand new car, then I would use sythetic oil becuase of the relative value of the investment, thus I can warrant the additional cost.
[ September 24, 2003, 12:15 AM: Message edited by: HondaRD ]