Hopefully the mechanic did bleed the brakes properly. If he just cracked each banjo union at the caliper and reservoir then you will have a lot of problems with air.

i had changed my oil to motul 3100 15W50(SS) a month back.
the oil level is little low as per the dipstick.

is it advisable to top-up the engine oil with Castrol 20W40(mineral) or should i get the motul 15W50?

20W40 is a different grade to 15W50. So you should never mix them.
Even with the same grade, you shouldn't mix engine oils from different manufacturers.
Its advisable you top up with Motul 3100 15W50 oil only or change your oil completely.

Cheers!!

What arijitmanica said, Don't mix your oils, you will end up with another grade/weight of oil.

Different oil manufacturers add different ingredients to their recepies.
Not sure if you remember the old Castrol advertising slogan (we had it back in the 1980-90's Australia) "Oils ain't oils"

Buy 2 bottles at a time when you change the filter. Your 2nd bottle can be used as a top up as needed. Also you can use it to lube other things on your bike (and around the house)

Hello All,
got a bit problem with the rear tyre.... I think the air pressure of rear tyre in going down a bit faster than expected. I maintained the pressure to 34psi. But after 2 days, after around 50km the pressure is showing 24psi. Is it normal? I checked the tyre for any puncture but could not find anything, also the valve is okay? Could u pls tell me the problem?

make a solution of soapy water. Get a rag or sponge and wet your rear rim. tyre contact patch, tyre sidewalls, tyre bead, rim, valve. You will find the leak then (and have a clean tyre after)

You can and should top-up your engine oil to correct level immediately . Semi-synthetic oil is mineral oil mainly with some synthetic in it really . You can use the castrol 20w40 you have for top ups (or any oil you may have handy) if you don't have any extra 15w50SS , no problem .

Say if I'd want to change my brand or grade of oil or shift from mineral to synthetic , would I need to take my engine apart and wash it clean of all the old oil ?
There is no such incompatibilities known between oil types/brands/grades . When we drain oil from the engine quite a bit of oil remains inside there and then mixes with the fresh oil we pour in . Manufacturers are aware of this and are unlikely to market an oil type that would cause problems to a new buyer (on mixing with the old oil) . The volume of oil used for a top-up is so small that it is less likely to affect the grade of the whole oil volume , than the oil degradation that occurs normally with use .
Riding with low oil levels on the other hand is inviting serious trouble .
The only way to detect a tricky leak for a tubeless tyre is to dismount the wheel and immerse it in clean water part by part in a suitable tub like the tyrewallas do . You'll see bubbles escaping under water from the leak . Do it slowly in good light and observe carefully since this kind of slow leaks bubbles very slowly too .

I disagree,

it is always recommended to top up with the same brand and same grade oil even tough the quantity may be very less... Even less of different grade oil is more than enough to change the way the rest of the oil would function in the system.

Topping up engine oil when needed is always important for the smooth functioning of the engine internals.

When one shifts to a major oil say from mineral to FS, the ideal way is to use engine oil flush and get the old oil removed from the system and then pour in the new oil.


Cheers,

Bro, oils dont mate to create off springs.
Oil gets its grade from the additives added to the base oil.
So 10w30+20w40 isnt 10w40. Its just part 10w30 and 20w40.
Feel free to correct me if am wrong.

Mixing oils

One should always try to keep same brand and grade of oil for top ups.
But it is not necessary - You can mix any w40 etc grades with each other. Try keeping same brand.

Mixing two different grades like w30 and w50 will make your oil neither belonging to w30 nor w50.. it will be somewhere in between.

Is it possible to remove all the old oil by doing an engine flush ? What about the flushing oil mix that remains back after it is drained ?

after 2k odo i changed from mineral 20W40 (YAMALUBE) to 15w50semi synthetic YAMALUBe..one thing that i found..while the engine is cold or before 10 k.m the engine is smoooth enough more than my expectation..but after 10km its rough while accelerating..no issue with chain.so what to do?

Bro same is the case with me.. I changed to SS 15w50 yamalube at 2300kms,after runin with mineral 20w40. but after the changeover...i feel great... its really smooth ,the engine cools down quicker than mineral and the ride is smooth on continious ride at 85-90kmph for 100kms.. no problem at all..

thats true even the engine produce heat is low than minarel

I am going to change to SS from mineral after 5k. Is it necessary to change the oil filter too?