Query approved.

@Sunil - Thanks for the approval.

Get the bottom welded, and that too with aluminium filler and a good reputed gas welder.

But the permanent solution would be to change the crankcase which is cracked/leaking.

@JD: Thanks for the tips. I had this problem earlier, however, all the previous incidents, it was always like 5 drops of oil on the floor, unlike this time where there was a pool of oil. Somehow, I'm not going to sleep today. Though I'm not that good with spanners, nevertheless, definitely going to give a try to change the washer and observe before giving up.

Sri, since I know a little on your Rx & the problem...
This is the best option, but IMO, DO NOT change the left side, as this is not the affected area. Change only the right side where the drain is located.

Hmm...ok, but, would that be fine with you? This is a patch work!!! Nothing gives a peace of mind with genuine replacements.

C'mon how will you do this? More over those guys WILL ask you to strip down.

There's a 3rd option ; Take my right side crankcase, its been lying idle here & it also has engine bearings in good conditions.

I like aargee's option no.3 Sri!

Update:

What a day! I came home around 5:30 AM from office and just could not sleep. Was waiting for some daylight before taking another look at my bike.
I thought it is better to waterwash first and start off my investigation.
Waited till it was 9:00 AM did a quick check to the service guy back of my residence. Finally, after couple of checks around 9:30 AM the water wash shop was open. Good 20mins waterwash and while it was almost getting dry, took my bike home.

Parked elevated with help of few slabs lying in my apt area. Guess what? It was not the drain bolt, it was not the welded part of the crankcase. Holly cow! the leakage was from the oil pump compartment. More than happy I was shocked looking at the crankcase outer cover leaking oil. Never thought that it would be from the oil pump compartment. My curiosity simply killed and did not wait another moment.

Opened the oil pump compartment and saw there was leakage from the pump assembly i.e the drain bolt. Well, I remembered that few days back, had filled side tank 2T oil which was empty. Offcourse was pre-mixing till I got the 2T. I pulled the 2T inlet tube to check then if there is a oil being pumped. That point of time, it did not. Thought it was air block since it was like a week running pre-mix while the tank was empty.

I wantedt to release any air block. While unscrewing, had a difficult time to get the star screw off since the bolt had some grove was chipped off. So gave some brutal force and got off the screw and oil flowed from the tank via tube.

Guess, this had some ill effect on pump. All the while after doing something like that, had been leaking which I thought it was from the gearbox.

Took a short nap and headed towards Y.A.S.S to find out if there is anything else that could cause the issue. Since I know the Manager there, was kind enough to ask someone to take a look. While service guy pulled out the oil pump, he observed that screw got jammed. He checked if this could be because of oil seal issue. He dismantled the entire pump and looked at the shaft inner where there is another oil seal sits. Oh man, that's the culprit. Though he was not able to conclude that due to my previous adventure might have led to the shaft to give away the small oil seal position.

I checked with the spares with regards to the shaft, which he said that i have been hearing for a long time 'WE DO NOT HAVE'. So packed the dismantled pump and safely took back home. I'm better off that it is not the crankcase issue which I feared the most this time.

Well, it was not the drain bolt or welded part. It is the damn oil pump created ruckus in the last 24 hours.

I know most of the RX owners would prefer going for pre-mix however, I'm from the old school, still wanted to have the oil pump in my bike.

This is not going to stop, now next step is looking for oil pump repair and the pains.

Oh!!! If its oil pump side leak, then it can be stopped easily. Its usually a broken oil seal that looks like...wait...I've one; I'll bring it tomorrow.

Guess it would be like bag full of parts . Will need some manual to re-assemble back for form.

No no, there's no bag full of parts Sri; open up side cover & inspect where the leaks are from. We can't take out the oil pump as it has oil seals to engine casing. As I told you, first thing to confirm is, if its 2T oil or engine oil that is leaking. Once that is found out, the solution will be easy.

mate. go get a new oil pump. even if you replace the seals etc, its a 12 yr pump ( i dont know the history ) and the aluminium parts inside do get worn out. Dont let this be the Achilles heel of the whole story. Plonk in a new pump and be good to go as new.

^^ @JD - Checked a little today, but couldn't really find out where it is coming from; we couldn't really spend time as there was something else that took priority. We're planning to work on this sometimes during one of the weekends this month or next. So when we work, pls expect a call from us (includes Bigbore & psycho)

^^ sure.. but do keep this in mind that lets not leave anything that could create issue later on.

+1 - that's the reason, I asked him to...throw away the oil pump lol & use premix.