Time for oil and gearbox oil change

HELP

I am an idiot and thought it was 500 hours before first service not 50.  Have just checked and of course I am now at 59 hours.

On looking through the paperwork(Beta 43)  I discover that I should have actually changed the gearbox oil at 25 hours.  I should also have been checking that dipstick too. (Didn't know there was one I am such a dipstick!)

Now what sort of oil should I get?  The manual says API CF (or CD CE) SAE 15W/40.

By chance I bought some Mineral Diesel Engine Oil 15W/40 API CI4/SL in case I needed to top up at any stage. Would it have been okay considering the remains of the previous is APICF4/SF or would it have been mixing two types.

Since I now have to do a full change now is it okay to use from oil change onwards?   (If so I need to get another one as 5l wont be enough anyway)

And the oil filter?  Is this a standard type on a Beta 43?  Can it be got from any Motor factors?


Also what about the gearbox?  PRM150  the book says below 0 degrees 10W30 or 20W Engine oil
0 to 30degrees 10W30 or 15W40 engine oil (I'll ignore the over 30degrees we are in england after all)

Can it be the same as whatever I end up putting in the Engine so I only need to have one sort on board for topping up purposes.

All/any assistance in this matter gratefully received ideally before I attempt the Trent again.

Plus should I get this service done by people who know or can a motorbike type person (not me) be able to do it without compromising my engine?