i switched to castrol synthetic a 100,000 on my truck and right now iam a lil over 108,788 and have had no probs, if u change oil when its do then it shouldnt be a problem just use a good quality oil

 

The only thing that would concern me about using a real good 100 % synthetic crank case oil on a high mileage motor is how dirty the engine is inside. I mean , how was it treated from the get go ? The concern is that the synthetics clean so well it COULD plug sh^t up in the process.

If you get a good deal on a used truck and want to run that good oil in it, I think it's a good idea to run a engine flush or pre-flush additive a couple times first. You don't want to cut off circulation , not even for a couple seconds.

If you get allot of scale peeling off the internals, oil pan wall or anything of that nature - that crap won't flow through the pick-up screen. However, it may plug it up. Just be carefull - Synthetic "blend" may be a wiser choice when buying a high mileage truck, not knowing what's it's been through.

I wish these oil pans where easier to remove

 

I used Mobil 1 in my previous car that I just p/x'd and apparently the inside of the engine was pretty clean. I changed to synthetic because the engines were prone to sludge as the design of the engine was not the greatest, but it worked well for me with no problems.