What exactly is this "rear main seal" you're referring to? Harleys don't have a rear main seal. If it was the left case seal, it was probably fixed in the receipts you reference.

Anyway, keep an eye on it and we'll figger it out. There's only 2 places it can go: Leak out or burn. You just have to find which one. And as mentioned, a quart in 1K miles is no big deal. A quart in 500 miles, well, there's issues. Also, some people suggest running the oil tank a little low, like at the "low" mark on the dip stick, as on some bikes that seems to help reduce oil lost out the vent. I think the '90 still had a 4 quart tank, so running it at 3.5 quarts certainly isn't going to hurt anything.

 

It's been on my mind a bit too. I did a top end, had my indi's machine shop hone the jugs with tq plates and I fit the rings myself. Broke it in properly, opened my rocker box drains internally and ran my breather hose up the backbone and down under the engine... No smoke, runs great and doesnt drip a drop... But, it needs a qt at 2k, pretty reliably.. I've got just about 58k on it (maybe 15k since the top) and spend allot of time on the hiway at 80+... I figure its the nature of the beast.. I run HD dino oil since new as well. With the exception of when I changed to a different oil a few years ago, it developed a tick I still have not gotten rid of.. Sounds like your in good shape..

 

I dunno what the P.O. meant by "rear main seal", he told me the motor was leaking oil out the "rear main seal" and the work order from the dealer in Philly stated "Replace Rear Main seal on motor".
I've alway refered to the seals as just "crank case seals".
I thought Harley tech had their own lingo?
I can tell you you are right about not quite filling the oil tank.
I changed the oil and being a "good doobie" put in exactly what they called for.
Fired the bike up and a few oz puked out the vent tube, all over the floor, ("GREAT! This Freakin' oil isn't cheap and now I've lubed the floor-again")
I took it out last night and to work today. Hey! this runs nice!
Short of a motor mount or???? squeak, (it's amazing what you hear when you quiet the exhaust down!!), that's annouying the hell outta me. (if I grab the motor and pull back-noise gone).
I'm gonna try to put SOME miles before the snow hits to see where I at and then this winter..............
Joe
" So Doc! If I take these pills, the voices telling me to smear peanut butter in my hair and run @ and sing Beatles tunes AND the alien abductions will stop??? Does this mean I won't wake up naked in farmers field naked anymore either? Great! Give me the extra BIG ones then".....