I just replaced my motor with one that has 89k. I want to switch to synthetic oil but dont want any leaks. give me an idea of things to change or do to ensure she runs strong forever. My other max had 221k and ran perfect.

 

If it has 89k, its already broken in.

 

If the other had 221k and ran perfect then why swap?

 

when you got the new engine, most of the seals and gaskets should be replaced. New RMS of course, oil pan seals and all that jazz. New seals all around should give you no issues going synthetic.

And realistically, I'd think just for peace of mind reasons you'd want to replace as many seals and gaskets as you could.

 

At 89K you'll probably be fine. That's still pretty low.

 

if it were me I wouldn't even bother besides valve cover gaskets and spark plug grommets. If its not leaking now why suffer through pulling all that stuff, retiming the engine etc. It just gives you more things that could go wrong if you make a mistake installing.

 

I would have replaced gaskets/seals before I installed the replacement engine.

 

there's no retiming... one of the reasons we're all here

 

Engine seals will degrade over time.
Todays synthetic oils do not make your engine leak oil.
Google that fact and you'll see where that originally came from.