I would stick with conventional. That's kinda high mileage to switch. I switched at 6K and have run synthetic ever since. I noticed a slight increase in MPG, and noticed my RPM's at highway speeds were about 1-2K lower.

The "synthetic high mileage" stuff isn't for doing swaps that late in engine life. It's meant for the person who ran it up until it was considered "high mileage".

But like everyone has said, it's your money.

I think it would cause something to leak. If you don't have any leaks now, you may if you switch.

I had a car one time that had over 180K on it. I added a can of "engine restorer", and changed the oil. Stuck with conventional oil, and had good luck with that. You might try "engine restorer", if you think your engine doesn't run like it used to.

 

I wouldn't worry about it, 129000 miles isn't really that much.

 

Its ok people. I took my truck a dodge dealership and they checked my engine and they don't recommend changing to synthetic either. I don't have any leaks right know, and like you guys said, it might start to leak.

 

Well you could always try a blend like motorcraft's. Nothing wrong w/ dino my dad ran his old chevy to 210k on plain dino w/ regular OCI's and it still ran great when he traded it.