I'm not an expert by any means, but sounds like something not right with the clutch/flywheel.
As for grinding going into R, does it do it if you put it in 1st then R? You should put it in 1st, then R
Mine doesn't always want to slide into R, but never grinds if I put it in 1st first.
Actually the only manual trans vehicles I've ever driven needed to go in 1st before they'd go into R easily.
Edit: I can't see from my phone, but if you have the ax15 (97-99), then the spec is for either 75w-90 gear oil or 10w-30 motor oil.
Be careful which gear oil you use, some are not safe for the syncros in the ax15.
Redline mt90 is supposed to be good...I've currently got Royal Purple 10w-30 motor oil in mine, which I really like.
Edit again: please fill out your profile so we know what you're talking about.
Also, considering you're in npr, I'd highly recommend heading to St. Pete & taking it to Jeepetos. If you're going to deal with any shop in your area, I highly, highly recommend Jeepetos. It's really not far off of 19 & doesn't take too long from npr.
If I were still in that area, I'd stop & lend a hand
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