FOMOCO466

I've ran full syn before I went 15,000 before changing the oil.... Before anyone says W H A T hear me out.... I changed the filter every 3000 miles. I ran Mobil 1 full syn, and the mobil 1 filter...... cleans 98% of the contaminats from the oil.... syn dosen't break down like regular oil does... hence less sut, sludge, ect... it only gets dirty, so install a new filter and keep on going. If the SEMI's can run full syn and hold 12 qts or more and go over a million miles without issue, and do WAY more with their rigs than we will EVER do... I've pulled a motor apart after running the full syn (which was installed after 12,000 break in miles) I had over 137,000 on the clock and you could still see the crosshatch in the cyl walls and no ridge to be had at the top of my 99 5.4.... always ran cool with never a hint of issues. also pulled 21 mpg at 70 mph in a 7400 lb Expedition 4x4 with a lift and 33x12.50x16.5's .... when my new truck gets the break-in miles done on it, it'll get the same treatment. If you pull the dip stick out and it still feels like oil, then let it go, if your fingers don't slide around then it's time to change. Also I agre with what one person said above... don't go back to reg oil after running full syn, the seals don't like it, and due to it running so clean, the sludge under the rings will be gone, letting the oil get by and it'll start smoking on ya. Haven't done it... but seen it.

Octane

Oil filters dont catch the fine particles, so you arent doing much good by changing the filter every 3,000 miles. The only way to get those out of your engine is by draining the oil.
To each their own, all I know is that on any of my vehicles I wont run the oil that long.
I tried using Amsoil and changing it every 12,000 miles on a '99 Ranger I had before I bought my F-150 and I'll never do it again.
When you have a brand-new truck with a proven, bulletproof motor (4.0L OHV V6) and its a quart low after only 6,000 miles, that makes me very skeptical of just how safe it is to run an oil that long.
I'll stick to using Motorcraft 5w-30 and changing it every 5,000 miles.
Also, the notion that you cant switch back to mineral oil after using synthetic is a bunch of BS. That was the case about 10 years ago, but with the formulations of synthetic oil that they have now you arent going to have those problems. I know lots of people that have flipfloped back and forth between mineral and synthetic and havent had any issues.

Moose08

yeah damn lol thats all i have to say, yeah no i couldnt do that, and as hard as i run my stuff i want it as fresh as possiable just knowing its been in there longer then 3k is like ah lol.

DLL66

You can go back to dino oil after using synthetics. I've used Amsoil for the past 8 years and I'm pretty satified with it.

cole_ford

I run synthetic, and one of the main reasons I started(whether its true or not, not sure) is because I heard it keeps the nasty tic that fords known for, away. And since then, its just become a habit using it on every oil change. And oil changes for me, run anywhere between 2500, and 3500 miles. sometimes even less, cuz i can go 4-6 months and only put on 2000 miles( I only drive 10 miles a day to work and back). I also feel better changing one extra time between NOV. and FEB. Trucks running a lot more during winter months. I dont know if synthetic has made my truck run any better though. For awhile I was usin ROYAL PURPLE, cuz I got roped into it by my brother, cuz he used it on his turbo'ed neon srt4, and said he gained a lot more power.