I let some fellow riders and 1 HD dealer talk me into synthetic on my 99 Heritage with 50k. I put Mobil 1 V-Twin 20W50 in and drained that crap out of there within less then 500 mile - "BIG" waste of money. Went back to Castrol GTX 20W50 and all is well again. Still have a very small weep at the left rear of the rear jug base and right front of the front jug base but it's a Harley.

 

] I'd like to say hello this is my first time on the site. the site is awesome. I just picked up a 98 ultra with the rear base gasket leaking. I heard a rumor that 3 m windshield sealant will help slow it down. I've never been a believer in the quick fix , but it actually works. it comes in a metal caulk tube at the auto parts store. mine was bubbling m blowing everywhere after I cleaned it up with brake cleaner very good I ran a bidet of sealant along the surface , making sure to hold it tight as to force it in the gap. that was a bout 500 miles ago and compared to what it was,it's dry. should have no problems getting through till winter as for right now, I'm slowly collecting gaskets and anything else I might need. I have 27,000 miles is there anything I should be concerned with at this point in time? pistons,lifters,rings? thank you for any help you could be and good luck with. The fix.

 

I think your engine has a timing chain & tensioners. They do require regular servicing but if I owned one, I would pull that Flintstones garbage out & run a gear drive system.
your mileage is low, your worries are a few years down the road!
welcome to the forum!!!
Hatch.