2002 GMC 1500: WalMart "SuperTech" High Mileage 5W30 whenever the "change oil" light comes on, probably ~6000 miles. It doesn't have an oil quality sensor, it just calculates based on RPM/temp/load/etc.
2008 VW Rabbit: Castrol Syntec European Formula 0W30 per the manufacturer's 10,000 mile specified interval.
1980 Buick LeSabre 4.1: WalMart "SuperTech" High Mileage 10W30, last done when I did the other two, and probably will do it again this summer. The car hasn't been driven.
I used to do 3 in 10. Now I think 5 k is not a problem with regular oil. The Mercedes SLK manual says service it once a year, so thats 10-12k on the oil. the engine computer determines the driving conditions and could result in earlier changes.
Man, I feel really bad for your LeSabre. I feel like driving up there and helping you give that car some "true love". My Buick loves to come out and play, and as a matter of fact I'm about to take her for a run to the bank. I'm the owner of a business worth millions, and I drive my deposits to the bank in a rusty old Buick...
In the Cressida I did 10k dino oil changes and 15k synthetic oil changes. In the Tracker I did 10k synthetic changes and the Durango will get it changed out in that fashion too unless the oil test shows it to be okay for longer.
Makes it easier to know when to change next. 40k, 50k, 60k, ect.
'95 Civic VX, mix of rural and highway driving, driving style between gas saving and normal, engine has 150k -ish mi on it, car and trans has 264k mi.
Used to do 3-4k mi changes, but noticed the car took no oil, so I figured I could stretch it. Even with the old smokey motor, still took very little oil when beating on it a lot.
Last oil change (now on "new" motor) was about 9-10k mi on Castrol Synthetic 5w30. Took about a half qt per 5k. Since then the valve cover seal has gotten leaky as well as the oil pan, so now it's taking a little bit more oil.
This time I have 4k miles on Mobil 1 5w30 and had to add about 2/3 of a qt. Oil leaks are getting a little bit worse, so once I fix those, I suppose the oil loss should go away.
On the never-ending quest for better gas mileage...
if its slowly startign to leak the bolts could have backed off with time/gasket getting a bit worn out, try lightly tightening then back down, my s-10 managed to get 2 of my valve cover bolts loose to the point of falling out.